Many Ashkenazi Jews later migrated, largely eastward, forming communities in non German-speaking areas, including Hungary, Poland, Lithuania, Russia, Eastern Europe, and elsewhere between the 10th and 19th centuries. With them, they took and diversified Yiddish, a Germanic Jewish language that had since medieval times been the lingua franca among Ashkenazi Jews. To a much lesser extent, the Judæo-French language Zarphatic and the Slavic-based Knaanic (Judæo-Czech) were also spoken. The Ashkenazi Jews developed a distinct culture and liturgy influenced, to varying degrees, by interaction with surrounding peoples, predominantly Germans, Austrians, Poles, Czechs, Slovaks, Kashubians, Hungarians, Ukrainians, Lithuanians, Latvians, Belarusians, and Russians.
Although in the 11th century they comprised only 3% of the world's Jewish population, Ashkenazi Jews accounted for (at their highest) 92% of the world's Jews in 1931 and today make up approximately 80% of Jews worldwide.[3] Most Jewish communities with extended histories in Europe are Ashkenazim, with the exception of those associated with the Mediterranean region. The majority of the Jews who migrated from Europe to other continents in the past two centuries are Ashkenazim, Eastern Ashkenazim in particular. This is especially true in the United States, where 6 out of the 7 million American Jewish population -- the largest Jewish population in the world when consistent statistical parameters are employed[4] -- is Ashkenazi, representing the world's single largest concentration of Ashkenazim.