The interplay between the different cultural centers in the medieval Jewish world can be seen in the case of the rise of the Babylonian Talmud as the prime authoritative source of rabbinic culture. The relation between Christianity and Judaism was unique and produced an encounter between medieval Christians and Jews that was both particularly intimate and particularly prone to tension, and even violence. While the juxtaposition between Jews “under the Crescent” and “under the Cross” may be too stark, internal differences within each of these political-cultural areas were significant and make broad characterizations problematic. The Christian attitude toward Judaism and the Jews had always been ambiguous. In the Carolingian Empire, Jews continued to enjoy the collective rights that they had under Roman law. The council’s decree suggests, of course, that socializing across religious boundaries must have been frequent and that in many parts of Christian Europe it was impossible to tell the difference between Jews and Christians.