History Marches On

History is for the most part not a mystery. Chronicles, legends, ruins, artifacts, and other forms of evidence have given us a pretty solid grasp of what happened in previous centuries. We know who fought which battle where and when, who ruled which country, who invented which device, who lived where, and who married which king and when.

And then sometimes we find out that we were wrong.

It isn't a common occurrence: most of our knowledge about the past is based on hard evidence. No amount of scientific innovation is going to change the date of the Battle of Vimy Ridge or the number of people who died in the sinking of the RMS Empress of Ireland. But some of what we believe to be sound historical fact is based on soft and sometimes unreliable evidence - hearsay, legends, traditions, opinions that have gone unchallenged due only to respect for authority and / or a lack of dissenting voices, reasoning based on data too fragmented to be unambiguous, and occasionally outright forgeries. When new discoveries or new methods of investigation or even new opinions on an event lead to the original belief being discredited among historians, the writer who based his work on contemporary history can be unfairly left looking like he Did Not Do the Research.

As you might guess, the more distant the subject in time the more likely this trope will come into play. We know more about any given day during World War II than we do about the entire reign of the Egyptian pharaoh Khufu (better known as Cheops), for instance.

Compare Science Marches On for when the same thing happens in science.

This trope is NOT for Alternate History stories where the writer deliberately subverts historical fact to explore the possibilities of a new timeline. Examples where a writer simply Did Not Do the Research should go in You Fail History Forever or Hollywood History. Examples where a writer deliberately misstates history to make it more palatable go in Politically-Correct History.

Prehistory

 * One of the first complete Neanderthal skeletons discovered is that of a male with a twisted, bent spine, a wasted lower jaw, and a pronounced hunchback. Archaeologists assumed this was a typical Neanderthal skeleton, which led to the popular view of Neanderthals as hunchbacked, chinless knuckle-draggers. Recent analysis has indicated, however, that the individual in question was probably well over sixty years old and suffered from severe arthritis and bone wastage. Most skeletons found since suggest that a Neanderthal would likely look very similar to a modern human (although they wouldn't be winning any beauty contests). Well-known works based in part on the old trope include Isaac Asimov's short story The Ugly Little Boy and numerous cartoons from Gary Larson's The Far Side.
 * Jean Auel resurrected the arthritic old man, named him Creb, and made him a great shaman-priest and Ayla's adoptive father in Clan of the Cave Bear.
 * It has also been assumed that Neanderthals couldn't speak, or that their ability to articulate was very limited, because the all-important hyoid bone was not found in any of the skeletons until 1983. Writers like Auel who wanted to portray them as intelligent usually had them use a sophisticated Hand Signals language. Now, it turns out they had hyoid bones all along.
 * In fact, it's likely that the modern human's version of the FOX P2 gene came from Neanderthals.
 * The Ugly Little Boy was expanded into a novel where one of the doctors goes into a detailed lecture about the hyoid bone. The Neanderthals are portrayed as having a language with click consonants, while Timmy learns to speak English—it just sounds a little blurry.
 * On a similar note, the infamous Piltdown man, despite being correctly guessed as a fake the year after its "discovery" and several times afterwards, wasn't completely discredited until four decades later. One of the main reasons being that many people of European descent, including respected scientists, simply couldn't fathom or palate that humanity's ancestor could have originated some place other than Europe or its near vicinity, much less Darkest Africa.
 * The notion of iron tools and weapons of the Iron Age being "superior" to bronze weapons, and, in particular, the notion of early adopters of iron weapons overrunning their neighbors with their new "superweapons". While iron has some properties that may make it more useful (its grain structure allows the tools to be resharpened, whereas a bronze tool must be reforged), most appraisals now seem to indicate that iron was used as a poor man's substitute for bronze as the collapse of most Bronze Age empires caused a loss of trade routes (and with them, tin).
 * A popular belief of early modern times was that Europeans could be divided into two groups: "white" Europeans from the north, known for rationality, intelligence, hard work, and integrity, and "swarthy" Europeans from the south, known for laziness, dishonesty, greed, and stupidity. Racial "scientists" later subdivided the swarthy Europeans into Mediterraneans and Alpines, the first of which was said to be creatively brilliant but lazy and shiftless, and the second stupid, plodding peasants. Despite the skepticism of most mainstream anthropologists and historians, the Nordic "master race" theory became a cornerstone of Nazism. Less horrifically, it also shows up in much of the fiction of the time: Conan the Barbarian might be the best-known example. Of course, we now know that Nordicism is bunk: not only do we now know that "Nordics" did not arise in Scandinavia (which was the last area of Continental Europe to be peopled), we also know that the various "white" Northern Europeans aren't particularly closely related to each other.
 * Europeans are actually quite closely related; it is just that there is little relative genetic distinction between "Nordics" and "Mediterraneans." Most western Europeans share the same paternal line of descent (Y-DNA haplogroup R1b) and most eastern Europeans share a different, but related paternal line of descent (Y-DNA haplogroup R1a). R1a is also quite common in central Asia and as far as India.

Ancient Egypt

 * Historians generally just assumed that the pyramids were built by slaves, since they couldn't imagine anyone working at such a difficult, back-breaking job voluntarily. This theory was exploded when archaeologists discovered contracts and other evidence showing that the pyramid builders were almost all free men. Historians now suspect that the pyramids were not just tombs but also enormous public works projects intended in part to give underemployed farmers something to do in the off season. Currently, the general idea seems to be that the builders were free men, but not doing the labor voluntarily—the government was taking their taxes in the form of labor rather than money or goods. Furthermore, they were building temples to their gods - and that might qualify them to be treated better in the afterlife. Still, virtually every movie set in Ancient Egypt gets this one wrong.
 * While there is still some serious dissent from this interpretation of the historical evidence, the Egyptians won't let anyone who claims otherwise go poking around the ruins for counterevidence.
 * Conventional historical wisdom had it that Hatshepsut was a wicked stepmother who stole the Egyptian throne from Thutmose III, the legitimate heir (and her nephew, son-in-law, and stepson), and had herself crowned King of Egypt. She supposedly allowed Thutmose to control the army but otherwise ruled the country with an iron hand until her death despite Thutmose being a competent adult for most of her reign. The proof? After Hatshepsut's death, Thutmose walled up all her inscriptions, tore down her statues, and obliterated her name from the histories - clearly, a sign of someone who had finally had enough of a meddling mother-in-law. Putting aside for the moment how unlikely it would be for a woman to stage a successful palace coup in 1514 BC when her opponent had complete control of the military, it was discovered in the 1990s that Thutmose didn't even begin to obliterate Hatshepsut from the historical record until twenty years after she died. Historians now think that Hatshepsut and Thutmose were friendly allies who ruled as co-monarchs, and that the elderly Thutmose or his son walled up her inscriptions because even decades after her death the people saw her as a more legitimate ruler than Thutmose. This has also put a few thorns into the common belief that Thutmose was Egypt's most successful and best-loved ruler. The trope is the basis of Pauline Gedge's novel Child of the Morning.
 * The supposed conflict even had some historians theorizing that Thutmose had arranged Hatshepsut's murder. Recent tests on her mummy show however that she likely died of cancer that either formed in the liver or spread there from an unknown primary location. There was also a flask of skin lotion found with her whose contents included benzopyrene, a potent carcinogen sometimes found in traditional eczema preparations.
 * Paintings dating back to the reign of Akhenaten (Amenhotep IV) show the "heretic king" with a large, flabby belly, unusually wide hips, and other features not often seen on healthy adult men. Until very recently it was assumed that these paintings portrayed Akhenaten accurately and that his unusual body shape was likely a result of either an intersex state or birth defects caused by generations of inbreeding. CT scans of his mummy, though, reveal that he was neither intersex nor deformed in any way. Historians now think that the body differences shown on the paintings were totemic - in other words, that Akhenaten was portrayed that way for religious purposes.
 * Likewise, his disestablishment of the state religion and proclamation of Aten as the one and only true God has been portrayed as a New Age revelation just short of Crystal Spires and Togas, a beneficent proto-Christianity, the inspiration for monotheistic Judaism, a megalomaniac's delusions, or even something his mom put him up to for political reasons. The most popular theory among historians was that it was due more to a feeling that the traditional gods had deserted Egypt (not only had the country endured a massive earthquake and tsunami but also a long series of pandemics) coupled with Akhenaten's desire to wrest power from the priests of Amun.
 * X-ray evidence showing splinters of bone inside Tutankhamen's skull once led historians to believe that the pharaoh was murdered by his vizier, Ay, as part of a palace coup. Recent scans of the mummy using modern diagnostic imaging devices have proved that the skull was splintered from the inside after death, probably as part of the mummification process, and that Tutankhamen likely died from a massive infection arising from a fractured leg (this does not disprove that Ay killed him, of course, but it does make it less likely—broken bones were not necessarily fatal even at that point in time). This mistake has shown up not just in novels but also in a few Video Games.
 * And is something of a plot point in The Egyptian.
 * And Mummies Alive!
 * And even newer evidence from DNA sequencing finds that Tut was the product of Brother/Sister incest, had malaria, and, if he had lived longer, would have developed a serious bone disease. Examination of his skeleton showed that unlike his father Akhenaten, Tutankhamen was deformed from inbreeding, by a club foot and slight cleft palate and overbite.

Classical Antiquity

 * All those marble statues, pillars, and facades found in Greek and Roman ruins were originally thought to have been as clean, white, and free of ornamentation when they were new as they are now. More recent tests on Roman ruins (and discovery of buried ruins at Pompeii, Palmyra, and Antioch) have revealed that the Greeks and Romans painted almost all of their white marble in loud, garish colors using vegetable-based paints that decomposed and bleached out as the buildings fell to ruins. This trope affected not just fictional representations of the old days but also architecture (notice how gleaming white the US Capitol is?) and interior design.
 * There was a similar notion about all Greeks and Romans wearing "noble" white clothes. While 'some' people actually dressed in white (e.g., Romans conducting in the forum), most people preferred the same garish, bright colors.
 * This is the Roman equivalent to assuming that the three-piece business suit or the full tuxedo is everyday casualwear for today. In fact, Romans hated the toga (they were hot in the Italian summers, cumbersome, and you can't use your left arm while wearing one) so much that there had to be a law stating that togas must be worn to enter a forum.
 * And carving statues from marble was more a Roman custom. Greeks much preferred casting them in bronze, and used marble mostly for smaller-scaled prototypes. Which is why Greek statues are generally known nowadays by their Roman marble copies—most bronze originals were melted for their bronze in Middle Ages (usually for cannons and church bells), and you couldn't melt marble.
 * Unfortunately for writers, historians seem to change their minds about Alexander the Great almost as often as the seasons change. Was he bisexual, homosexual, or heterosexual, and does it matter that he wouldn't have recognized the terms? Roxane Roxanne  Roxana Roshanak: passionately desired wife or all-but-ignored political pawn? Bagoas: manipulative poisoner, victim of child molestation, or adult lover? Hephaestion: lover, colleague, or rival, or all three? Alexander's death: poison, typhoid, meningitis secondary to scoliosis (the 2009 belief), or accident? Was he Too Good for This Sinful Earth, a Magnificent Bastard, or a Complete Monster? Given the historical revolving door, it would be hard to fault a writer for making up his own mind about any of it.
 * The 2010 suggestion was that he died of West Nile disease.
 * In 2012, it's waterborne parasites. See what we mean?
 * The history of Troy. Up to the times of the Renaissance, Homer's account of The Trojan War (minus the machination of the gods, of course) was treated as historical truth. But as scientific archaeology was being established, Troy was relegated to myth. Right now, most archaeologists agree that a bronze age city once existed at the site where Troy should have been based on clues in Homer, and that some sort of battle did occur there.
 * As early as the first century, a man claimed that the battle did occur... but the Trojans won.
 * There is even a theory that the Iliad and Odyssey are in fact Alternate History, in which the real retreat after years of battle gets a twist ending tacked on. The Fridge Brilliance in this is that most of the interactions with gods and mythical creatures in the stories center on Odysseus, the man that also came up with the twist ending horse trick. It's like someone added the character for storytelling purposes.
 * On a related note, Pompeii faded into obscurity to the point it was considered a myth by the time its remains were discovered in the 18th century. This despite the fact that 1) it disappeared in much more recent times; 2) it disappeared at a time with extensive written records, including those of first hand witnesses, and 3) one of the most famous and read Roman scientists and authors of all time, Pliny the Elder, died when studying the disaster in situ. The account of the eruption by his nephew, Pliny the Younger, was still considered bogus well into the 19th century when eruptions in other countries happened the exact same way as he described the one of 79 AD. Because of that account, this kind of eruption (pyroclastic explosions with a tall column of ash and pumice but little liquid lava) is commonly known to vulcanologists as a Vesuvian or Plinian eruption.
 * Speaking of Pompeii, change in sensibilities have allowed the publication of rather explicit images that were on display on the city; which changed popular perception of the Romans from a genteel, prim, proper, and moral people to a debauched, hedonistic people. Archaeologists and historians believe that Roman sexual taboos were as strong as ours, just completely different in nature, and that Romans were considerably more open and frank about sexual matters than we are.
 * The Christian shrine in the Roman Colosseum (formerly known as the Flavian Ampitheatre) has tripped up many writers and readers. The ruins of the Colosseum were consecrated in 1749 by Pope Benedict XIV, supposedly in memory of the many early Christians martyred in that location. But Christians were never martyred at the Colosseum; even the editors of the Catholic Encyclopedia could find no definitive proof. There's a possibility that Nero's massacre of Christians after the Great Fire took place on the land on which the Colosseum was later built, but it's more likely that Benedict XIV invented the entire story in order to justify protecting the building from property developers looking to turn it into a wool factory.
 * Cleopatra VII was once seen as a scheming, amoral Femme Fatale whose sins led to her death and to the destruction of Egypt as an independent nation. Recent evidence from Alexandria and a reappraisal of the historical record has led many historians to believe that Cleopatra saw seducing Caesar and Antony as a legitimate way of convincing them to help restore order in a country quickly approaching lawlessness and poverty while at the same time preventing Rome from invading and enslaving the populace. The discredited trope informs everything from William Shakespeare's Antony and Cleopatra and Julius Caesar to the paintings of Alexandre Cabanel and Guido Cagnacci.
 * Historians were once also divided over whether Cleopatra was the most beautiful woman to ever live or an outright Gonk. There was no middle ground. Recently, though, historians actually decided to look at the damn coins Cleopatra minted, and concluded she was an average-looking young woman—no great beauty, but nothing to be embarrassed about either. More recently, they've done facial reconstruction with a computer, which shows that she was plain but cunning-looking, which seems appropriate considering that contemporary accounts said she was had a bewitching voice and a strong, forceful personality.
 * For the longest time, people have assumed that Cleopatra had numerous slaves bitten by the asp she'd later kill herself with to make sure that its venom was potent. She didn't need to: the Egyptians had used snakes to kill upper-class prisoners for thousands of years, and they knew what breed to use and how. They were also quite aware that an asp that's already bitten numerous slaves isn't going to have enough venom left to kill a fly.
 * And some scholars now believe that the asp story is a cover-up, and that Cleopatra was killed on the orders of Octavian.
 * In the eighteenth and nineteenth centuries, as religion further faded in academia and it became clearer that much "contemporary" writing about early Christians was medieval interpolation, many historians, including as prominent as Edward Gibbon, came to believe that all references to the persecution of Christians were fabricated, the Romans paragons of religious tolerance. Ultimately, due to archaeological findings and better techniques of textual analysis, this belief has only a very few holdouts.
 * Carthage was probably not salted after the Third Punic War. The idea appears to come from confusion over a medieval order calling for the city of Palestrina to be ploughed over "like Carthage," and also salted. Carthage itself was certainly ploughed over, but the idea of it being salted doesn't turn up until the nineteenth century.

Ancient Levant

 * Most historians now doubt that Judah and Israel were ever a single united kingdom under the House of David (or Saul, or a confederation under the loose rule of the Judges). Considering that the source material was for many years considered too sacred to question...
 * The census which led to Joseph's journey to Bethlehem (and the birth of Jesus in same city) has no documentation in historical Roman records. Nor does it particularly make any sense by Roman standards (requiring Jews to travel to the city of a distant ancestor would have involved separating them from every quantifiable source of income, making such a census useless for tax purposes; the Roman censuses we know of involved census takers traveling from city to city instead of the reverse). The earliest known Gospel by modern standard, the Book of Mark (the book of Matthew was once considered older, but that in and of itself is another History Marches On), begins with Jesus' baptism and ministry and completely ignores his life prior to that. In the modern day, the Nativity story is often thought of as a literary device to ensure Jesus' birth in Bethlehem (the city of David, ancient king of Israel and presumed ancestor of the Jewish Messiah) despite his lifelong association with the city of Nazareth in Galilee.
 * Actually, there were several cities called Bethlehem (it's a rather general name meaning "food storage"). There is one much closer to Nazareth. The problem with him being born here, however, is that it erases the connection to David that the entire story seems intended to support. Unsurprisingly, Vatican objects to excavation attempts.
 * The Synoptic Problem, as briefly mentioned above. Basically, the Gospels of Matthew, Mark, and Luke (the "synoptic" gospels, meaning "same eye"), all agree on the basic structure of Jesus' life, and contain much material (the Triple Tradition; almost all of which is the "biographical" portion of the three Gospels) that is the same word-for-word. In addition, there is a considerable amount of other material that is shared between Matthew and Luke, but not Mark (the "Double Tradition"; this is mostly "sayings", among them the Lord's Prayer and the Beatitudes). The problem, so to speak, is attempting to determine which of the Gospels came first, and whether the other two knew of each other. In the 5th century, St. Augustine of Hippo proposed a hypothesis that Matthew was the first of the three written, Mark was an edited version, and Luke copied from both of them. This is still the official position of the Roman Catholic Church (due to the tradition of the Book of Matthew being written by one of the Apostles), and the ordering of the Gospels in modern Bibles comes from this hypothesis. Many scholars would later come to reject the theory citing Mark's overall shortness, relatively crude Greek, and the fact that Matthew and Luke don't really seem to agree on anything outside of the common material, and often interpret the common material in different ways. Several other theories about the order have been proposed over the years, with the current majority behind the "two source" hypothesis: the book of Mark came first, and the books of Matthew and Luke copied independently from Mark and a hypothetical "sayings" source, often referred to as "Q."
 * This can often go the other way too. People thought that Balthazar from the book of Daniel was made up, until historical research unearthed that he was King Narbondius' son and co-regent of Babylon. While his father went out to face Cyrus' army, Balthazar stayed behind to fortify the city. Cue the writing on the wall.
 * The discovery of the Nag Hammadi Library in the late 1940s really shook up the world's image of the early history of Christianity, as they contained the scriptures of a long-extinct sect of Christianity called the Gnostics, who had a radically different view of God and Jesus than traditional Christianity. These sources also contained several Apocryphal texts — gospels that failed to make the final cut and weren't included in the Bible.
 * Conversely, the notion of "Pauline" Christianity coming into prominence very late after Jesus' death and squashing differing accounts is also considered apocryphal by most historians. While Gnosticism, Nestorianism, Arianism, and other alternative approaches to Christianity certainly did exist, they only really obtained prominence outside of the Mediterranean "civilized" world, and were swallowed up by orthodox movements (or later, Islam), with very little incident as later migrations brought those peoples into the Roman sphere. In a similar vein, the Gospel of John (and the linked Epistles I, II and III John) was often thought to have supported a dualist Gnostic worldview; discovery of the Dead Sea Scrolls (which, contrary to common knowledge, contain no New Testament works or anything at all related to Christianity) suggests John was instead using rhetorical devices similar to those used by the Essenes.

Medieval Times

 * First of all, Columbus was not the first foreigner to make landfall on the Americas. The Vikings beat him there by some five hundred years. And the Chukchi people had been crossing from Alaska to Chukotka (part of NE Asia) for millennia, across the Bering Sea.
 * Currently anthropological and genetic evidence point to America actually being populated, originally, by people who entered from Asia. Theories for the route include the Beringian land bridge—at certain points in the ice age, there wasn't any Bering strait—and the seacoast south of the land bridge.
 * The complete lack of anybody other than Native Americans—no, not even Vikings—living in the Americas when Columbus arrived didn't stop racist Europeans from declaring that no Native Americans could have built the Mesoamerican pyramids or the Mississippian mounds. No, they must have been a "lost race" of Europeans. Even attributing them to "Giant Jewish Toltec Vikings" was considered more plausible than admitting that Native Americans built them. Such racist notions were finally discredited by 20th-century scientific archaeology.
 * The same thing happened in Africa; when Great Zimbabwe was "discovered" by Europeans, it was taken as proof that whites had always ruled southern Africa since obviously only white people could have built something like that. This was the official line of the Rhodesian government well into the 1970s, and they persistently censored the publications of archeologists who disputed this.
 * Secondly, in the Medieval times, people not only knew Earth was round, they knew (and had known for 1,000 years) how big it was. Columbus, however, got that wrong. He underestimated the size of the globe and overestimated the size of Asia, so that the distance that he predicted between Europe and Asia was much shorter than in reality. (That's why all those monarchs before Isabella refused to fund him: they were right and he was wrong.) He and his sailors would have died en route if not for his big stroke of luck: an entirely unknown land mass at just about the distance from Europe that he predicted.
 * Some claim that Columbus didn't so much get the size of the globe "wrong" as "shaved a third of the established value off to make it a better sell."
 * This particular theory is used in Orson Scott Card's novel Pastwatch: The Redemption of Christopher Columbus, which describes Columbus desperately looking at ancient records to try to find "proof" that his size of Earth was the correct one. He is pretty obviously shown to be disregarding any piece of evidence to the contrary. Interestingly, the novel shows that by the time he brought his case before the Spanish royal court, his case was solid enough to rival the established proof, leaving the tie-breaker up to the Queen, whom he convinced by his sheer piety. Also, according to the novel, Columbus thought he was looking for China, not India, because.
 * Despite the modern associations with the word, Gothic architecture wasn't at all that dark; churches used to be painted bright colours, and there was plenty of light. After centuries, the paint faded away and everything was covered in grime and dust and the colours were lost. Emulators in later centuries built buildings that looked like the old churches ended up looking, with all the gloomyness and intimidation that entails, that wasn't originally even there.
 * Actually one of the properties of Gothic cathedral structure was big windows (between pillars). Big windows means a lot of light.
 * The Dark Ages weren't nearly as backwards as Renaissance and Enlightenment scholars claimed. Even the phrases "Dark Ages" and "Middle Ages" are going out of style: both were invented by the same scholars to emphasize the glory of the ancient world and the nobility of the scholars who reached for it, in comparison to the ignorant fools who laughed at their theories, yes, laughed, but they'll show them, they'll show them all. Historians are now more likely to use the phrases "early medieval" and "late medieval" ("medieval" is derived from the Latin for "middle age", so you have to wonder if it just sounds cooler).
 * Those Renaissance scholars and especially the enlightened scholars apparently put in a lot of work to 'prove' how little books had been written in the Middle Ages: by throwing away anything written in that time-period. Later researchers bought into the propaganda and genuinely believed nothing of note was written during Medieval times. They also introduced the idea of Medieval people being obsessed with religion when it seems they were mostly pretty laid-back about the whole thing. It was the Renaissance people who were the overly religious nutjobs (keep in mind they were the ones who cared enough to break off from the mother church).
 * The supposed fall of Western culture was once thought in part to have been caused by a series of massive tribal migrations collectively known as the "Volkerwanderung". Specific examples included the migrations of the Saxons, Angles and Jutes to England; the Lombards into Italy; the Vandals and Visigoths into Spain; and the Franks into northern France. The belief was that these tribal migrations displaced the original inhabitants of these areas, sending them into less hospitable areas (such as the supposed "Celtic fringe" of the British Isles) and disrupting cultural progress. But DNA comparisons of ancient and modern peoples show very little evidence that the Volkerwanderung ever occurred; modern Englishmen, for instance, are far more closely related to ancient Britons (and to modern Scots, Irish, and Welshmen) than they are to modern Saxons. This DNA evidence is so new that historians are still grappling with the implications, but one possibility is that the Volkerwanderung only displaced the elite - about 0.5% of the population in most areas - leaving the bulk of the population unaffected except by the consequent cultural changes.
 * Another theory is that people did move, but only a little, with people abandoning their old homes but resettling close-by. It does indeed seem that the massive relocations all over Europe that historians once saw as fact never really occurred.
 * One of the strangest results of the recent DNA comparisons is the discovery that Europe contains two genetic outliers - two ethnic groups that are less closely related to Europeans in general than others. One, not surprisingly, is the Finns, who trace their origins back to what is now Asian Russia. The other? The Italians, who have less in common genetically with the Spanish, Romanians, French, etc. than do groups that were never part of the Roman Empire (such as the Ukrainians or the Irish). Nobody has yet come up with an explanation for this seemingly impossible result.
 * This comes up over and over again in archaeology: Some researchers seem to believe the only way ideas and cultural influence can spread is via conquest. For example, older literature quite often gives the impression that the whole of the Neolithic was one giant exercise in cultural imperialism as zealous farmers left North Africa and the Middle East en masse to convert the rest of humanity from their hunter-gatherer ways.
 * Likewise, the view popularized by Sir Walter Scott's Ivanhoe of plucky "English" commoners still resisting their "Norman" overlords a century or two after the conquest has likewise been shown to be hogwash - but that doesn't stop it showing up in most Robin Hood adaptations, where the Sheriff's soldiers are referred to as Normans to make it OK for Robin to kill and wound them. The idea either dates to the Hundred Years War, when Henry V's propagandists started to play up an imaginary antagonism with France (despite Henry's whole claim in that war being based on his being, you know, a member of the French royal family), or to the Reformation, when it was even more useful to play up a nationalist narrative.
 * Such was the strength of this, incorrect, legend, people were referencing the 'Norman yoke' which had supposedly derailed incontrovertible English freedoms as justifications for rebellion in the 17th century. There was no sense of Norman and non-Norman by then, but it was a handy reason to demand more rights. Walter Scott was clearly on a well trodden path when he penned his work.
 * The fact that the Norman/Saxon distinction eventually evaporated as they blended together doesn't mean that the "Norman yoke" of, say, William the Conqueror didn't exist or that the Conquest wasn't a loss of English freedoms. See the "Harrying of the North".
 * For centuries it was assumed that Europe's first introduction to plague (the Black Death) was in 1348-1350, when roughly one-third of the population died. Nobody knows exactly when plague arrived in Europe for the first time, but recent scholarship suggests that plague was behind many ancient epidemics, including the Plague of Justinian and the pandemics that affected Egypt in the time of Amenhotep III and Greece in classical times.
 * Plague can infect people in three ways: through the lymph system ("bubonic plague"), through the lungs ("pneumonic plague"), and through the bloodstream ("septicemic plague"). Most of the descriptions handed down to us by medieval doctors describe bubonic plague, so it was once thought that it was the most common form; many people even today think that "bubonic plague" is the correct name for the disease. But the main reason doctors described bubonic plague so often was because bubonic plague victims lived long enough for the doctor to arrive, unlike victims of pneumonic and septicemic plague who generally died within hours of the first symptoms. Meanwhile, evidence from the 20th century plague pandemic supports the idea that pneumonic plague is actually slightly more common than bubonic.
 * Everybody Knows That people in the Middle Ages loved to burn witches—it was like their version of the movies. Go into town, do some shopping, and then stop to watch some witch burnings. Good times. Except this is another of the things manufactured by later philosophers to elevate their own times over the so-called Dark Ages. The medieval Catholic Church actually considered it heresy to believe in witches—that's right, accusing a woman of witchcraft would likely get you in trouble. It was only late in the Middle Ages when the Church declared witches to be real, and it's the supposedly enlightened Renaissance and Reformation when the witch burning craze took off. Incidentally, burning was primarily a continental thing—in Britain (and Salem, Massachusetts) the punishment was hanging.
 * Witchhunts were in fact a very Protestant thing during the Reformation, while the Catholic world remained generally apathetic about it (the main exception being France). So if you are planning to follow Dan Brown and write a story about poor girls being rounded and burned by the Corrupt Church because they are feminists ahead of their time that know the truth about Mary Magdalene, consider that for example, the entire number of witches burned by the terrible Spanish Inquisition was 12. In a single trial in 1609 directed by a French inquisitor that was sacked after it, and after which the whole existence of witchcraft was declared bollocks by his superiors. Essentially the Inquisition was too busy killing Jews and Protestants to bother with peasant superstition.
 * The Spanish Inquisition actually spent very little time killing Protestants and "crypto-Jews/Muslims" and did spend most of their time correcting peasant superstitions. Because the Church in Spain was reformed 20 years before Luther, and all of Luther's works were banned, Protestantism never really spread to Spain. Instead the Inquisition spent most of the latter half of the Sixteenth century correcting folk superstitions in rural Spain (and not by torture, amazingly enough). It's true they were a surprisingly small organisation with little effect outside the cities in which the minority of the population lived. Most (approx 70%) of the cases brought before the Inquisition dealt with lapses of morality and general sexual misconduct, and most of those concerned ordinary Spanish people. The other 30% dealt with charges of religious ignorance which they strove to correct. Roughly 3% would concern people brought up on full charges of heresy and fewer still were burnt. The Inquisition sought primarily to educate ordinary people about and uphold the faith, not to go around burning witches and heretics. That said, we have no idea how many people in Portugal, Castile and Aragon were tried and hanged as witches by local authorities and nobles acting under their own jurisdictions. The number could be in the thousands, but the records simply don't exist.
 * Contrary to popular belief, witches were hunted not by Inquisition (that was formed to fight heresy) but by the local, secular authorities as witchcraft was a common crime like murder, assault or theft. Inquisitorial courts actually had no jurisdiction in such cases, unless the witch was not also accused of belonging to the heretical cult.
 * The Inquisition was the first judicial body in Europe to have established rules of evidence, recognize an insanity plea, ban arbitrary punishments, and dismiss anonymous accusations. It was actually closer to modern jurisprudence than most secular courts of the Middle Ages and Early Modern periods.
 * Joan of Arc, by the way, was not burned as a witch. Her crime was relapsed heresy, having to do not with her voices but with her cross-dressing. She signed something promising she would never again do so, then her captors stole her skirt and replaced it with pants; it was either that or go naked. Anyway, her real crime was leading the French to victory, anything else they accused her with was just an excuse.
 * In fact, the vast majority of "accepted knowledge" about the Medieval period has turned out to be patently untrue - as it was heavily based on the accounts of Protestant and Enlightenment writers, who would fabricate information or present hearsay as fact to advance their point of view. The Middle Ages (as known by historians nowadays) were a colourful epoch, sporting many significant advancements in science, a lot of cultural crosstalk (Gothic architecture, almost synonymous with the Middle Ages, was inspired by Indian and Arab/Muslim building styles) and not nearly as much dirt as later accounts would have you believe. The problem is that Reneissance writers - whom most accounts of Middle Ages were originally based on - considered the entire epoch between Antiquity and them to be just like recent history - and recent history was Black Death and Hundred Years' War. Several myths still endure, but several popular history books have now been published which popularize the scholarly view of the matter.
 * Indeed, Early (10-13 centuries) and High Middle Ages (14-15 centuries) could be called a times of prosperity, and some retaking of the Roman heritage (the deed the Renaissance authors were so proud of) already started to happen. But then the Black Death arrived, and with it a whole host of new wars and plight, that ended that nascent boom.
 * The media following King Solomons Mines that feature lost and always foreign civilizations in the mists of Darkest Africa have their roots in the plain racist interpretation of Great Zimbabwe after its discovery by Europeans in the late 19th century, that stated the place was "too advanced" to have been built by "obviously primitive" Black Africans. This view was debunked as early as 1905.
 * When the far-right white-minority regime came to power in Rhodesia, they promoted the myth of Great Zimbabwe as having been built by a "lost" European civilization to the extent that archaeologists excavating there had their work interfered with by the government who were keen to suppress anything which contradicted the official story.
 * The Benin Bronzes were apparently also the subject of crackpot "lost civilization" nonsense by European racists who refused to believe that they had been created by Africans.

Renaissance and Early Modern Age

 * Catherine de' Medici was one of the cruelest royals of the early Renaissance. She followed the (in retrospect, probably sarcastic and retroactive) advice of Machiavelli, to ensure that her husband and three of her sons ruled France; hundreds of noble and wealthy Frenchmen died either directly at her hand or otherwise. She even arranged for her son Charles to be sexually abused by courtiers in an unsuccessful attempt to turn him gay so that he would die childless and his younger brother Henry (whom she adored) would eventually become king. Given her deservedly bad reputation, it's not surprising that contemporaries in England blamed her for instigating the St. Bartholomew's Day Massacre. Screeds called her a "Catholic bigot" who washed her hands in the blood of innocent Protestants. Modern historians, on the other hand, believe that the massacre was actually instigated by the Guise family, who feared Catherine's alliance with the Protestant Navarre family. But TV still holds on to the old belief, as can be seen in shows such as Elizabeth R, The Tudors, and Godfathers of the Renaissance.
 * Machiavelli, author of The Prince, was a staunch supporter of the concept of a free republic. Unfortunately The Prince was his only well-known piece for a long time. Now it is known that he was most likely a satirist, because that was his only pro-Medici screed, and after writing it, he went right back to writing pro-republic stories.
 * He was also often portrayed as a cynical, somber and shrewd politician. Contemporary data, including his letters and works portray him rather as a very sociable satirist who also happened to be an observant historian and a good rhetor.
 * Contemporaries viewed Lucrezia Borgia as a scheming, amoral poisoner who abetted her father and brother (Rodrigo and Cesare Borgia, respectively) in their Machiavellian plans to dominate Europe. This belief became even more prevalent in Victorian times, when the word "borgia" entered the dictionary as a synonym for "sadistic female poisoner". More recent scholarship has cast doubt on this belief, as there is no historical proof that Lucrezia herself ever harmed a flea, let alone committed multiple murders. If anything, Lucrezia's life might have been a lot easier if she had been a poisoner. It's thought now that Lucrezia was blamed by her contemporaries because unlike her less innocent relatives, she was a safe target.
 * And then there's the Borgia's supposed poison, la cantarella, a potent yet undetectable brew whose formula could be adjusted so that the victim could die at any time the poisoner wished. Too bad it's not actually possible for such a poison to exist given the limitations of Renaissance science and the unpredictable response every individual will have to a specific toxin. Roderigo probably used plain old arsenic while Cesare and Giovanni disposed with subtlety, strangling their enemies and throwing them in the Tiber.
 * Did we mention that the Borgias were no more murderous than any other prominent Italian family of the time? They got the bad rep because they were social climbers, not because they were especially evil or because their evil was hereditary. Which is a good thing for Tom Cruise, since Brooke Shields is a descendant of Lucrezia Borgia. Of course, that Shout-Out in The Prince certainly doesn't help...
 * The fact that Borgias were Spanish also wasn't helping in getting sympathy from Italian aristocrats.
 * The Spanish film Los Borgia shows that Lucrezia was only used as a way for the family to ally with powerful families, and then canceling those marriages when they weren't useful anymore.

Modern Times

 * It was originally thought that George III suffered from mental illness, probably caused either by inbreeding or immorality, since all crazy people at the time were thought to be immoral monsters. Historians are now fairly confident that George suffered from a blood disease called porphyria, since many of his descendants suffered from the condition and his symptoms were virtually textbook. Ironically, the type of porphyria George is thought to have suffered from is caused by one dominant gene, so inbreeding had nothing to do with it.
 * When 1776 was written, not a lot of information about James Wilson was available. The playwrights looked at the writings they had, and tossed in a bit of Artistic License, creating a climax where his desire to remain a nobody is the crucial factor in him breaking with Dickinson and voting for independence. They note in the DVD Commentary that this story choice was never singled out by historians as a major misstep, but later findings show that James Wilson was actually a staunch proponent of independence, and that the delay in the vote which the play attributes to stalling techniques by Adams was partially due to Wilson wanting to go home and check that his constituents were all right with his vote.
 * Like George III's porphyria, Queen Victoria's status as a carrier of hemophilia was also originally blamed on inbreeding. As is the case with George's porphyria, hemophilia is caused by a single mutated gene and is therefore not more common in inbred populations. The mutation is believed to have first occurred spontaneously in the gametes (=eggs/sperm) of either of Victoria's parents, making her the first person in her family ever to have the mutation. Thus, inbreeding would have absolutely nothing to do with it. If anything, it's interbreeding with Victoria's daughters that spread hemophilia to so many other nations' royals, whether they were previously related to her or not. American television shows love this trope, though.
 * Speaking of inbreeding, historians are beginning to wonder if Victoria was really as closely related to her husband Albert as everyone assumed. They were supposed to be first cousins - Victoria's mother was sister to Albert's father - but German historians have pointed out that Albert was the spitting image of his mother's lover, Alexander von Hanstein, who was unrelated to the royal families of Germany. If this is the case, Victoria and Albert would have been fourth cousins - and fourth cousins share no more genes on average than any two unrelated persons.
 * It's not at all certain but at least one alternative theory in recent years is that van Gogh was actually shot accidentally by someone else.
 * Painters and musicians of the 18th and 19th century were captivated by the concept of the Turkish harem. They were enraptured by the idea of hundreds of beautiful young concubines or "odalisques" loitering around in various states of undress, fawned on by cringing slaves and guarded by eunuchs, all existing solely for the pleasure of the Sultan. The best-known works influenced by this are probably Mozart's Abduction from the Seraglio and Ingres's Grand Odalisque. We now know, of course, that the Real Life Turkish harem was very different from the imaginings of these artists; most inhabitants were older female relatives of the sultan or of previous sultans, and the concubines that did live in the harem were often left to wither on the branch, most sultans being either too old, too drunk, or too disinterested to make use of them. Even the term "odalisque" was used incorrectly: in Real Life odalisques were the slaves tasked with looking after the harem's older inhabitants, and were often chosen from the least attractive women at the slave market.
 * Virtually every story of Irish immigration to America in the 19th century describes the many "No Irish Need Apply" signs that sprouted up in American cities, denying Irish immigrants the right to work and housing. There's no denying that the Irish, like all immigrant groups, were the subject of some pretty nasty prejudices, but the "No Irish Need Apply" signs? There's no evidence that they existed in the United States. The historian who examined the myth did find two want ads specifying that Irish not apply - that's two ads, both for household maids, in seventy years of American publishing - but every supposedly "historic" sign he was shown turned out to be a modern replica. (You can buy them on eBay should you feel the need to own one.) He thinks the belief was derived from a music-hall song called, unsurprisingly, "No Irish Need Apply", which was written about the situation in England in the late 1700s. Even then, nobody's sure if those signs really existed or were, again, another early urban legend.
 * This was the time when Dutch colonists were noted and occasionally mocked, and then there were "weird" Protestant sects like Quackers or Mormons... when you add the economical tensions leading to The American Civil War, slavery and political disagreements, it's obvious that the U.S. market of "whom you don't like" was already overstocked, and there was no particular reason why everyone at once would choose to single out the same group over their existing pet grievances.
 * The RMS Titanic sank on a dark, moonless night. Most survivors who had escaped in lifeboats thought they saw the ship sink in one piece, while the few survivors closer to the ship and struggling in the water to survive said they thought it broke in two. The inquiry into the sinking accepted that the survivors in lifeboats had a better vantage point, and it became accepted fact that the Titanic sank whole. In 1985, however, the ship was found on the ocean floor in two pieces, surrounded by a debris field that could only have been created by the two pieces separating at or near the surface. All movies about the sinking filmed before 1985 show the ship sinking whole, while only the 1997 movie shows it splitting up before sinking.
 * And now there's speculation as to the extreme angle of the ship before it split, with many historians now claiming that it wasn't as high up as originally thought before it split in half. Not quite as exciting.
 * And then there's the way it split. Analysis of the blueprints of the Olympic-class superliners suggests the Titanic likely broke apart from the bottom up, not from the top down. Also, a big chunk of broken-off hull was recently discovered on the seabed, beyond the main debris field.
 * And now, yet more studies of both the debris field, have shown that it was indeed most likely a split from top down, as chunks of the ship from the area where the split happened have been found on the ocean floor. Also further investigation of the keel plates have shown damage caused by the bow pulling down, eventually pulling out the rivets.
 * There was also the issue of the size of the wound the iceberg made. For years it was assumed that it had torn a gash in the side of the ship. Dr. Ballard's expedition proved that the iceberg actually caused the hull to buckle, forcing rivets to pop out and separate the steel plates.
 * On top of that, there's considerable debate over the quality of the steel used in her construction. Ever since it was found that the steel had a high sulfur content, some at first thought that low-quality steel had been used in an attempt to cut costs. However, more recent evidence has come to light suggesting that not only was the steel of much higher quality, but it was also some of the highest quality steel available at the time. Unfortunately, the steel-manufacturing methods of the time hadn't quite yet gotten to the point of reducing the amount of sulfur content in steel...
 * The bad quality might also be attributed to the enormous amount of steel needed, leading to subcontracting to unexperienced metal-workers.
 * A 1981 episode of the Leonard Nimoy series In Search Of asks the question "Will we ever find the Titanic?" The answer turned out to be "yes" just four years later, making the episode date very quickly. And, of course, the experts interviewed for the show assumed the Titanic sank in one piece and idea that it broke in half was not even suggested.
 * Recent study of World War I era documents suggest that there never really was a "Schlieffen Plan". New writings from archives in the Soviet-controlled sector of Berlin have revealed no evidence to suggest that Count von Schlieffen had a rigid plan to defeat France within M-42 before turning on Russia. The Germans only moved into Belgium in 1914 because it was anticipated that the Entente would do so anyway.
 * It was speculated for decades that Russian Grand Duchess Anastasia survived the execution of her family by the Bolsheviks. This was the inspiration not just of two films titled Anastasia but also of numerous Real Life pretenders who claimed to be the Grand Duchess. Eventually, investigators were able to find and exhume the mass grave the family was buried in and proved conclusively through DNA testing that Anastasia was killed with her family in 1918.
 * Even after the grave was discovered, there were still two bodies missing, that of Alexei (the only son) and either Anastasia or her sister Maria. However, in 2007, charred remains of a boy and girl were found nearby the mass grave, and in 2009 they were proven through DNA testing to be the bodies of Alexei and one of his sisters, proving definitively that all of the Romanov family was killed by the Bolsheviks. Sorry, Anastasia fans!
 * Remember Rasputin? The mad monk who was poisoned, beaten, and shot in the head four times before being thrown in the Neva River, and when they fished him out they discovered that he'd drowned? Turns out that the entire story was a tissue of lies. The autopsy report (which was discovered after the fall of the Iron Curtain) shows that Rasputin was shot in the head by a .455 Webley, a gun normally issued at the time to British Secret Intelligence Service officers, and died instantly. There was no evidence of poison, no evidence of pre-mortem beating, and no evidence of drowning. Whether he was killed by the SIS or whether Prince Felix Yusupov, who had close ties to the British government, used a British gun to kill him, will probably never be known, but the entire story of poisoned cakes and wine and the indestructible mad monk seems to be a complete invention.
 * A lot of sugary food can act as an antidote to cyanides, so there's that.
 * Mussolini did not make the trains run on time.
 * For a while after World War Two, it was an assumption that Nazi Germany was efficiently-run because of its fast ascension from economic devastation to infamously cruel conqueror of Europe; in Star Trek: The Original Series episode "Patterns of Force", for instance, this view led to believe he could make it work without the ethical problems. Since then, however, a lot of evidence has drawn historians to the conclusion that the regime was full of internal corruption and egotistical rivalries, and about as (in)efficient as you might suspect an oversized bureaucracy to be.
 * In many cases, even more inefficient: when the Nazi economy was looked at post-war, it was discovered that the country was on the verge of economic collapse prior to World War 2, which was delayed by the merger with Austria (providing some economic buffering), and delayed again by the bloodless conquest of Czechoslovakia, which was essentially looted. By 1939, without any other free targets to exploit to shore up the economy, military conquest was the only thing left preventing economic meltdown.
 * The Gestapo was also portrayed as a ruthlessly efficient political police. In reality, they were constantly understaffed and overworked and could only count on helpful German citizens or paid informers in the occupied countries. Also, no intimidating black outfits. Being the members of secret police Gestapo officers usually operated in plain clothes, on rare occasions they wore unassuming gray police uniforms.
 * It was worse than an oversized bureaucracy, given that it was built on corruption and promotion of yes-men from top down (starting from the Fuhrer's "old friend", junkie Goering); also, the chain of command was split, and then tied in knots.
 * One variant that frequently crops up in media (and politics) is the Guilty Men (a British anti-appeasement polemic written after the outbreak of war) interpretation of Neville Chamberlain and the appeasers in Britain and France - a small, craven, and idiotic clique that hijacked their nations in the 1930s. This interpretation was challenged as early as the 1960s by A.J.P Taylor, and current historical opinion is divided, with some historians saying appeasement was the right call, others saying that it was the right call but poorly executed, and a small minority saying that Britain and France should have (with no provocation) invaded Germany in 1933. Almost all agree that the appeasers were men of compassion, humanity and courage, if (depending on interpretation, misguided). But try telling that to all the Films, Books, TV shows and political leaders who portray them as stupid cowards.
 * One reason for the plethora of Stupid Jetpack Hitler conspiracy theories is that, for a long time after the war, it was believed that they Never Found the Body. Various people put forward theories that he had survived, whilst most historians, such as William Shirer and Hugh Trevor-Roper, felt that it was more plausible that he had been buried in a mass grave (some even theorized, on good evidence, that he ended up in the Jewish cemetery). It didn't help that the Soviets also saw the propaganda value in claiming that the Western Allies were sheltering him. With the fall of the U.S.S.R, it has now become apparent that they did find the body, and preserved skull and jaw fragments, which were confirmed by Hitler's dentist. The corpses were buried under a parade ground in Magdeburg, and were exhumed in 1970, burned, crushed and thrown in a river.
 * The view of the 'Stalin Note' amongst most western historians went through this twice, ending up about where it began. The first view was that Stalin was not serious about wanting a united neutral Germany, and did it mainly to sour relations between Germans and the West. Then, in the early 80s declassified documents indicated that the western powers had not always acted in good faith about the offer, leading to a shift towards viewing Stalin as more serious about his offer... which lasted until the end of the Cold War lead to declassified Soviet documents that indicated that the main Soviet goal had been to sour German-Western Allied relations. In case you had doubts about whether Comrade Stalin took the whole "World Revolution" thing seriously and could see which powder keg is the easiest to set on fire.
 * The identity of Deep Throat, the principal informant of Bob Woodward and Carl Bernstein who helped unravel the Watergate scandal, was a mystery for thirty years. In All the Presidents Men he's portrayed as an anonymous figure in a trenchcoat; in the film Dick (1999) "he" is actually two teenage girls. In 2005 Deep Throat was revealed as former FBI Associate Director Mark Felt whose motives were likely revenge against Nixon for not promoting him to replace Hoover.
 * Carlos the Jackal is the Big Bad of the Bourne Series, which presents him as a Diabolical Mastermind and attributes a number of assassinations to him, including that of JFK. The actual Carlos was captured a few years ago, and is now viewed as more of a bumbling Smug Snake whose past reputation was highly exaggerated. This also account for most of the differences between the books and the movies (he had been caught by that time).
 * Imperial Japanese "Comfort Women" are widely mentioned in fiction, but after decades of never bothering to examine it closely because the Imperial Japanese did enough warcrimes they were never given the benefit of the doubt, historians finally started examining the case and completely failed to find any actual evidence they existed outside of Korean propaganda, instead finding that Korean kidnappers and Korean parents sold women to Korean owned brothels that were simply visited by Japanese soldiers. The South (yes, the supposedly free South) Korean government forces all citizens to tracked online via their social security number and arrests historians to keep this knowledge from spreading within the country (among other reasons).
 * Several widely repeated stories from within the Nanking massacre, most notably the famous "contest to kill 100 people with a sword" are considered fake, causing historians to push the exclusion from modern sources because their fakeness throws skepticism on everything else.