Yeah. Yiddish-speaking Jews are not "indigenous" as it were to Eastern Europe, as opposed to the small population of Turkic Jews. That's part of the reason why the Russian Empire distinguished between the Yiddish-speaking Jews of the Pale (subject to all kinds of legal restrictions) and the various other, ethnically Turkic, small Jewish peoples of the Empire (which were not). Like I was mentioning before, AFAIK that's when the whole "descended from the Khazars" trope started to get important, because the Turkic Jewish groups argued that they were the descendants of the Khazars*, who were CONVERTS to Judaism, and so did not share ancestry with the Yiddish-speaking Jews who had killed Christ.
* and they quite possibly are.
--- On Fri, 7/18/08, moominek at aol.com <moominek at aol.com> wrote:
>
> Truly not a myth: The language of East European Jewry, the
> Yiddish, is more a german dialect out of the middle ages
> than anything else:
> The big migration to the east started with the plague
> progroms in the West around 1350.
>
> Sebastian
>