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. The Jewish oaths were the judicial oaths demanded from Jews involved in litigation when summoned to appear in a Christian court as plaintiff or defendant. The Jewish oath, as a judicial phenomenon, was an essential instrument enabling the integration of the Jews, who were traditionally exempt from undergoing trials by ordeal, into the legal system, and through it, into economic life. It enabled the Jews, in spite of their being not simply aliens but also nonbelievers, to purge themselves like all freemen by taking an oath. As in most aspects of Jewish-Christian relations, Spain differed considerably from the European nations. In all of the early medieval laws there was complete equality between Christians and Jews.