Some Chabad communities are now a mix of Ashkenazi and Sephardi Chabad Hasidim. New developments in Judaism often transcend differences in religious practice between Ashkenazi and Sephardic Jews. They found similar results analyzing DNA from Ashkenazi and Sephardi Jews. The community consists of people of Ashkenazi and Sephardi descent. It had both an Ashkenazi and a Sephardic synagogue. Ostrer also refuted the Khazar theory of Ashkenazi ancestry. Some scholars believe that the Sicilian Jewry are partial ancestors of the Ashkenazi Jews. H6a1a1a is common among Ashkenazi Jews. Concerning the theory of Khazar ancestry in Ashkenazi Jews, the authors found no direct evidence. Later German immigration brought large communities of Ashkenazi Jews. "Yiddishkeit" is specifically the Jewishness of Ashkenazi Jews. Greenblatt is an Eastern European Jew, an Ashkenazi, and a Litvak. The name is Yiddish, the historical language of Ashkenazi Jews. It functions as an umbrella organization for Ashkenazi Jews. Efforts to identify the origins of Ashkenazi Jews through DNA analysis began in the 1990s.