They established communities throughout Central and Eastern Europe, which had been their primary region of concentration and residence until recent times, evolving their own distinctive characteristics and diasporic identities. In the late Middle Ages the center of gravity of the Ashkenazi population, and its traditional cultural life, shifted steadily eastward, out of the German lands into Poland and Lithuania (including present-day Belarus and Ukraine). In the course of the late 18th and 19th centuries, those Jews who remained in or returned to the German lands experienced a cultural reorientation; under the influence of the Haskalah and the struggle for emancipation, as well the intellectual and cultural ferment in urban centers, they gradually abandoned the use of Yiddish, while developing new forms of Jewish religious life and cultural identity.
Is there an answer to this question (If it cannot be answered, say "unanswerable"): In the late Middle Ages, as the Ashkenazi population shifted it moved into which location?
Poland and Lithuania (including present-day Belarus and Ukraine)