Five years later, a new Jewish community took root in the narrow, winding streets and by 1354, the city funded new houses and a synagogue, drawing Jews from across Europe to Erfurt. “That must have convinced them it would never happen again,” says Karin Sczech, an archaeologist who works for the city.

For 100 years, Erfurt’s Jews flourished. In 1454, the town council revoked the rights of Erfurt’s Jewish population, forcing them to leave town. The city built a granary on top of their cemetery, destroying hundreds of graves and repurposing Jewish tombstones to build its stout stone walls, reports said.

Before the remains were reburied last year at a nearby cemetery, their DNA was extracted and it showed the origins of the Ashkenazim, the major Jewish population that emerged in Germany in the Middle Ages and later expanded into central and Eastern Europe.

The latest study on DNA from the six individuals from the Middle Ages unearthed in Norwich offers clues to where the Ashkenazim came from centuries earlier, and what happened along the way. The studies confirm that today’s Ashkenazi Jewish population, which numbers more than 10 million people spread around the world, has roots in about a few hundred who survived a population bottleneck in Europe more than 1000 years ago.

The mystery remains: Were the Jews of Erfurt belong to the Roman era? Or were they the descendants of some pioneers who crossed the Alps around 800 C.E. to found tight-knit communities along the Rhine, near modern-day Frankfurt?

“Ashkenazi Jews emerge in the Rhineland as migrants,” says Leonard Rutgers, a historian at Utrecht University and a co-author on the Cell paper. “But if they came from elsewhere, where did they come from?”

“Whether they’re from Israel or New York, the Ashkenazi population today is homogenous genetically,” says Hebrew University geneticist Shai Carmi.

Earlier, Carmi was pessimistic about studying DNA from ancient Jews. “I thought this would be impossible,” he says, “because there would be no permission to sample.” Searching for ancient DNA for analysis would mean grinding up tiny bits of bone for sequencing. Destructive sampling would also be needed for radiocarbon dating. “It’s a hard rule in Judaism that you don’t disturb the dead,” says Alexander Nachama, chief rabbi of the Jewish Community of Thuringia and head of the modern-day Jewish community in Erfurt.

Carmi pressed ahead, contacting historians and archaeologists in Europe to see whether suitable samples existed. “The historians thought I was crazy,” Carmi says. But a few got back to him—including Sczech, who had received rabbinical permission to measure bones from the Erfurt cemetery to determine their sex and ages at death, techniques that don’t harm the skeletal material. Carmi was able to sample the loose teeth of 38 individuals from the cemetery before the bodies were reburied in a 2021 ceremony.

The DNA results from Norwich and Erfurt both confirm that modern Ashkenazim are descended from a small founding population. Based on modern Jewish DNA, some researchers had speculated this founder group emerged from a population crunch in the 13th and 14th centuries, when the religious fervor of the Crusades and false accusations that Jews spread the Black Death sparked violent pogroms. But the new data point to a different scenario that played out earlier.

In the Norwich individuals—which DNA shows included three sisters and a young boy with red hair and blue eyes—geneticists found the same disease markers seen in modern Ashkenazi populations, at about the same frequencies.

At the same time, small differences among the dozens of Erfurt genomes suggested medieval Ashkenazi communities weren’t completely homogeneous, despite the earlier bottleneck.

That mixture of east and west “is exactly what we get from the genetic results,” Sczech says: After first branching out from a single, small founding population into small communities across Europe, including medieval Great Britain, the medieval Ashkenazim apparently mixed back together in places like Erfurt generations later.

The role of Jews as bankers, craftspeople, traders, and money lenders would have put them in constant contact with their Christian neighbors. In Erfurt, as in many medieval cities, synagogues, ritual baths, and Jewish houses were in the heart of town, right next to the city hall and at the intersection of two major roads.

Archival records show Jews and Christians went into business together and Christians served as wet-nurses to Jewish children. “Jews and Christians were constantly in each others’ lives. But it looks like they didn’t have children together,” Baumgarten says. “We as modern people don’t have the words to describe that complex sense of belonging.”

“It’s fair to say Jewish history is one big sequence of bottlenecks,” Rutgers says. But the Erfurt data suggests a brighter possibility: that long before the Erfurt Jews were laid to rest, somewhere in Europe a few dozen people flourished, passing their genes and culture to millions of people living today despite a history of brutal persecution.