[jimwatx]

They lived in the medieval era, about 600 to 800 years ago, according to the analysis – and numbered just 350 or so people.

Jewish persecution during "the Crusades" was said to have begun around 1096 in and about the Rhineland, were these not Ashkenazis then or what am I missing?

[Pharmboy]

I don’t think you’re missing much...as you know there were 3 major Crusades, and these might have had a small part in reducing their numbers, but the Black Death likely had a larger effect.