Ashkenazi are Jews who lived in the Europe. They once lived in the area of Rheinland and France and after the crusades they moved to Poland, Lithuania and Russia. In the 17th century, avoiding percecution, many Jews moved to and settled in the West Europe.
After that, two terms, Ashkenazi and Sephardi, became commonly used: The former indicates the Jews who worshiped in the German way, the latter indicates the Jews who worshiped in the Spanish way. They differ in language (pronunciation), cultural tradition and worship style.
Thomas A. Idinopulos(1994), Jerusalem: A History of the Holiest City as seen Through the Struggles of Jews, Christians, and Muslims, Dee, Ivan R. Publisher, ISBN 9781566630627