Language of Ashkenazic Jews and their descendants (see Ashkenazi ), written in the Hebrew alphabet .
Yiddish developed from southeastern dialects of Middle High German carried into central and eastern Europe beginning in the 12th century; it has been strongly influenced by Hebrew and Slavic languages , particularly Polish and {{link=Ukrainian language">Ukrainian , led to a primary distinction between West and East Yiddish dialects. From the late 18th century most Jews remaining in central Europe gave up Yiddish in favour of German; it has now virtually died out. East Yiddish dialects differ markedly in realization of vowels; there are central, northeastern, and southeastern dialects. A flourishing literary language in the 19th and early 20th century, Yiddish declined dramatically due to suppression, massive migration, assimilation, and Nazi genocide. The language nevertheless continues to flourish among the ultra-Orthodox Hasidim in numerous countries and among secular students of Yiddish at leading universities, including Columbia University (New York), Hebrew University (Jerusalem), McGill University (Montreal), the University of Oxford, and the University of Paris. Yiddish is spoken by three million people worldwide.