"The Ashkenazic communities gradually spread to other parts of Europe. Torah students from the core communities of Speyer, Worms, and Mainz went on to become Torah leaders in neighboring lands. Some examples are France (Rashi and others), Bohemia and Austria (the Or Zarua and others), Poland (Maharam Mintz, R’ Yakov Falk, and others), and Italy (the Shibolei Haleket, Mahari Mintz, and others).
"In general, these communities continued to practice Ashkenazic customs in the lands they spread to. As a result, we refer to all European Jews — except the Spanish, Portuguese, and those Jews who came under their influence — as “Ashkenazim.” An indication of their Ashkenazic origin is the obvious linguistic link between Yiddish and German."
Machon Moreshes Ashkenaz
Rabbi Binyamin Shlomo Hamburger
Translated by Rabbi Reuven Poupko