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. In the medieval sources, the term "Jewish king" applies both to a person who effectively reigned over a territorial realm and to a man called "king" as an honorary title bestowed upon members of some distinguished families even though he did not rule a land or its people. The recognition by respective Jewish communities of individuals or families as descendants of the dynasty of King David qualified various medieval Jewish leaders to be called "kings", although they did not use the royal title. The most important, and genuine, branch of the Davidian dynasty was the family of the Mesopotamian Exilarchs, from the third to the thirteenth centuries.