In August 2017, hundreds of white supremacists descended on Charlottesville, Virginia, for a violent rally that killed one woman and injured at least 19 others. They bore images and chanted slogans that evoked Nazi Germany, the Confederacy and the Ku Klux Klan. But they also carried symbols from an even older time—symbols whose origin they did not seem to understand.

One man carried a round shield decorated with a black eagle. It was a curious choice, considering the eagle image is strongly associated with a Saint Maurice, a Roman general of African descent who became a saint in the early Middle Ages.

“Nazis aren’t very happy that I keep posting the *original* medieval European bearer of this standard, Saint Maurice,” tweeted Malisha Dewalt, who runs a blog about people of color in European art history. In that tweet, she attached a side-by-side comparison of the man in Charlottesville holding his shield and Saint Maurice holding a flag with the same eagle on it.

The white supremacist in Charlottesville carrying that image was probably unaware that it’s strongly associated with a Black Catholic saint, and this disconnect illustrates a larger trend. Hate groups that adopt medieval iconography as symbols of white supremacy usually have misconceptions about that historical era. One of the most common? That Europe in the Middle Ages was unvaryingly white.

“The understanding of medieval Europe as a homogeneously white space is completely erroneous, as scholar after scholar has shown time and time again,” says Cord J. Whitaker, a medieval literature professor at Wellesley College who is writing a book called Black Metaphors: Race, Rhetoric, Religion, and the Literature of the Late Middle Ages.

Recent work by archaeologists and anthropologists “shows beyond a shadow of a doubt, Northern Europe in the Late Middle Ages—even the Middle Ages generally—was an incredibly diverse space,” he says. In 2015, when researchers at the Museum of London analyzed the skeletons of four people who lived in Roman London between the first and fifth centuries, their groundbreaking investigation found that one of them had Near Eastern ancestry, and another was likely born in North Africa. In a 2013 roundtable interview for NPR, art historians also noted that medieval art is more racially and ethnically diverse than many people assume.

So if medieval Europe wasn’t really an all-white space, why do so many people think it was?

“Much of that misconception comes from modern popular treatments of the Middle Ages, really beginning in the Enlightenment,” Whitaker says. Many non-white figures in medieval art were either ignored or physically edited out of the picture. And popular 19th-century novels that focused on medieval Europe portrayed it as a primarily white place.

“Many of those 19th-century texts were bound up with modern British and other European forms of colonialism and imperialism,” he says. “They’re very much bound up with naturalizing the idea that Europe is an ancestral homeland for Europeans, that it was homogeneously European in heritage, and that it should have power over the rest of the world.”

Which is not unlike when modern hate groups link medieval images to white supremacy. As an example, Whitaker points to the othala rune. This symbol—which looks a bit like a fish pointed upward—was originally just a letter in a medieval runic alphabet. But in the early 20th century, Nazis took it up as a symbol of white supremacy. Last year, the National Socialist Movement, an American neo-Nazi group, replaced the swastikas on its uniforms and banners with the rune. The Anti-Defamation League lists it as a hate symbol.

“This is something that’s very much in keeping with the legacy of the 18th and 19th centuries, which was the height of European imperialism around the world,” Whitaker says. When neo-Nazis display the othala rune, they’re evoking the idea that Europe is the “ancestral homeland” of white people like them—and no one else.

Whitaker recently discussed white supremacists’ use of medieval icons at a symposium called “The Crusades, the Middle Ages, and the Alt Right.” The symposium was organized by Matthew Gabriele, a professor of medieval and early modern studies at Virginia Tech, who says historians need to address hate groups’ use of medieval iconography. Often, this imagery comes from the Crusades.

He saw it in footage of the Charlottesville rally, he says: “The imagery that these white nationalist, white supremacist groups were using was really in a lot of cases very noticeably medieval.” Some of them carried “crusader shields with a red cross on it that said ‘deus vult’”—a Latin rallying cry meaning “God wills,” used by some Christian knights in the first Crusade. The red crosses evoke those worn by the Knights Templar, a Roman Catholic order that has long been fodder for myth, legend and conspiracy theories.

Hate groups’ attempts to link modern Islamophobia to the Crusades plays off of “a much older, 19th-century style of scholarship which portrayed the Crusades in a very specific way,” Gabriele says. This older scholarship framed the Crusades as a “Christian defensive war against an aggressive, expansionistic Islam.” Hate groups use this narrative of the Crusades to say, as Gabriele puts it, “‘Look what happened then; it’s happening again now.’”

Only it’s not happening now; and it didn’t happen that way then, either, scholars say. As Suleiman A. Mourad, a professor of religion at Smith College who spoke spoke at the symposium, points out, the Crusades weren’t just a series of wars between Muslims and Christians for the Holy Land. Rather, they consisted of multiple factions vying for control.

“Every story is complicated, and every story has multiple narratives,” he says. “If we simplify them, we are ignoring and sidelining important details.”

But the fact that hate groups use medieval symbols out of context isn’t the only reason historians should be troubled, says Susanna A. Throop, a professor of medieval history at Ursinus College who spoke at the symposium, too. They should also be concerned with “how history, which is a product of historians’ work, is being deployed to promote a specific vision of the future,” she says.

Because even if medieval Europe were homogeneously white, and even if the Crusades were really just as simple as Christians versus Muslims, that still wouldn’t justify racial or religious genocide. “History can and should inform our ethics, but it doesn’t determine them,” she says. “And the relationship between history and our present ethical decisions is not always simple and straightforward.”