Fresh DNA research has confirmed that Jewish remains discovered in a Norwich well were casualties of a medieval pogrom.

Researchers said the new findings further help to pinpoint the period when genetic disorders prevalent among Ashkenazi Jews first began to appear.

The remains, containing the bodies of at least 17 people, were happened upon in 2004 at the Chapelfield shopping centre construction site in the East Anglian city.

It was initially speculated that the remains were of people who had died due to disease or hunger but analysis of the bones found little evidence of this.

Research undertaken in 2011 for the BBC 2 TV series History Cold Case, found that the remains were likely of Jews and that they were left in the well sometime in the 1100s or 1200s.

It suggested that the remains may have been of Jewish individuals killed in a pogrom but, the findings were not deemed conclusive.

They also discovered that there were fractures to the adult remains and not the infant ones, suggesting that older victims were thrown down the well headfirst, prior to the younger ones. 

Writing in the academic journal Current Biology on Tuesday, Dr Brace a researcher at London's Natural History Museum argued that more detailed radiocarbon dating analyses of the remains and pottery fragments discovered with them suggest they were deposited between 1161 and 1216.

This period overlaps with the antisemitic violence of 1190 that engulfed Norwich, Stamford, Lincoln, and York, chronicled by Ralph de Diceto’s Imagines Historiarum II.

The medieval cleric described how in February 1190 “many of those who were hastening to Jerusalem” to partake in the recently launched Third Crusade were “determined first to rise against the Jews,” and that: “All the Jews who were found in their own houses at Norwich were butchered; some had taken refuge in the castle”.

“Ralph de Diceto's account of the 1190 AD attacks is evocative, but a deep well containing the bodies of Jewish men, women, and especially children forces us to confront the real horror of what happened,” co-author Dr. Tom Booth explained.

Other eruptions of anti-Jewish violence characterised the high medieval period in England, including Hugh Bigod’s 1174 sack of Norwich in which the city was plundered and torched, and many of the city’s Jewish inhabitants attacked. Several decades prior in 1144, the first distinct blood libel charge of ritual murder was brought against Norwich’s Jewish community.  

The high medieval period in England spanned from the Norman Conquest to the death of the final Angevin King, John, in 1216. It also marked the emergence of documented Jewish presence in the region, following sparse or circumstantial evidence available from the Roman and Anglo-Saxon periods.

DNA analysis advances also allowed the team of biologists to piece together entire genomes for six of the people discovered in the well.

“When we look at the DNA from [the remains], they’re actually more closely associated to modern day Ashkenazi Jews than to any other modern population,” Dr Brace told The Guardian newspaper.

The study said the genome sequencing of the remains confirms that three of the victims were full-sibling sisters, including a young adult, a girl aged between 10 and 15, and another aged between five and 10. All had dark hair and brown eyes.

The analysis found, too, that one victim was a young boy with red hair. 

It marks the oldest ever sequenced genomes of Jewish remains, given strict prohibitions regarding the disturbance of Jewish burial sites.

The research also suggests that the “bottleneck” among the Ashkenazi population occurred earlier in the diaspora split than previously thought, given that the remains contained far more affinity with modern Ashkenazi genes than expected. 

A “bottleneck” is when a sudden decrease in population size increases rare genetic variants in a given group, events widely thought to have impacted the genetic make-up of current Ashkenazi populations.

Given the smaller presence of the same genes among today's Sephardi Jewish communities, this means it is likely that a major Ashkenazi "bottleneck" took place before the 1300s to 1500s.

“It was quite surprising that the initially unidentified remains filled the historical gap about when certain Jewish communities first formed, and the origins of some genetic disorders,” UCL Professor and co-author Mark Thomas said in light of the fresh findings.

Dr Brace said that the remains had been buried in Earlham Orthodox Cemetery back in 2013.