Little is known about the history of Ashkenazi Jews before they were expelled from the Mediterranean and settled in what is now Poland around the 12th century. On average, all Ashkenazi Jews are genetically as closely related to each other as fourth or fifth cousins, said Dr. Harry Ostrer, a pathology, pediatrics and genetics professor at the Albert Einstein College of Medicine in New York and the author of “Legacy: A Genetic History of the Jewish People” (Oxford University Press, 2012).
“Ashkenaz” in Hebrew refers to Germany, and Ashkenazi Jews are those who originated in Eastern Europe. (Sephardic Jews, by contrast, are from the areas around the Mediterranean Sea, including Portugal, Spain, the Middle East and Northern Africa.) About 80% of modern Jews have Ashkenazi ancestry, according to the Hebrew University of Jerusalem. Albert Einstein was an Ashkenazi Jew, as were Gertrude Stein and Carl Sagan. Steven Spielberg and Scarlett Johansson are also Ashkenazi Jews, along with three current members of the U.S. Supreme Court (Ruth Bader Ginsburg, Stephen Breyer and Elena Kagan).
Source: Los Angeles Times
The major non-Jewish contributors to the ethnogenesis of the Ashkenazic Jews were Slavs, though there was probably also a minor Turkic strain — both in the Caspian-Black Sea area (the descendants of the Khazars, a mainly Turkic group that converted to Judaism in the eighth century) and in the Balkans and Hungary.
In all of these areas, the Turkic population early became submerged with the coterritorial Slavs. In addition to Yiddish terms of Slavic, Greek, Romance and German origin which express aspects of the Jewish religion and folk culture, the book shows that many elements of Ashkenazic folklore and religion themselves were of Slavic origin — either West (Sorbian and Polabian) or Balkan Slavic. There is a lengthy discussion of the evidence for widespread conversion to Judaism in Asia Minor, southern Europe and the Germano-Sorbian lands up to the twelfth century and the reasons why pagan and Christian Slavs converted to Judaism. While historians have been disputing the extent of conversion to Judaism, Wexler thinks the linguistic and ethnographic evidence make the conversion evidence highly plausible. In addition, Jewish linguistic evidence refutes the traditional claims that Yiddish is a variant of High German and that Modern Hebrew is a “revived” form of Old Hebrew; new hypotheses are proposed: that Yiddish began as a Slavic language (specifically a Judaized form of Sorbian) that was re-lexified to High German at an early date, and that Modern Hebrew is, in turn, Yiddish that became re-lexified to Hebrew, and thus is also a form of Sorbian. These facts support the author’s hypothesis of the Slavic origins of the Ashkenazic Jews, and the bulk of their religion and folk culture.
(the Sorbs are a West Slavic population that still numbers about 70,000 in the former German Democratic Republic).
Source: The Ashkenazic Jews: A Slavo-Turkic People in Search of a Jewish Identity (Slavica Publishers)