This chapter focuses exclusively on medieval Jewish civilization, from the fall of the Roman Empire to about 1492. It includes alphabetically organized entries, written by scholars from around the world, include biographies, countries, events, social history, and religious concepts. "Ashkenazi ?asidism" is the traditional appellation, adopted also by modern scholarship, for the groups of esoteric theologians, mystics, and teachers of ethics who flourished in medieval Germany, mainly in the Rhineland, between the middle of the twelfth century and the end of the thirteenth. According to Rabbi Judah, the text of the prayers is not that of communicative language conveying meaning. The Ashkenazi ?asidic concept of ethical behavior expressed an achievement of total spiritualization of the nature of Jewish worship and social behavior, without weakening the adherence to the practical and physical aspects of Jewish observance. In the period of the Geonim in Babylon almost all writing was done in Arabic, at first in Arabic script and later in Hebrew script.