The vitalization of western christendom that began toward the end of the first Christian millennium had, as an unanticipated consequence, development of what was to become eventually the modern world's largest set of Jewish communities. As Christian armies eliminated Muslim enclaves from European soil, Jews long resident in the conquered areas elected to remain under Christian rule. Other Jews, impressed by the newfound dynamism of Latin Christendom, chose to immigrate, strengthening old and small Jewish communities in southern Europe and founding new Jewries in the north. By the year 1500, a considerable Jewish population had emerged in Christian Europe, although Jews had been expelled from the more advanced sectors of western Europe and pushed eastward into the less developed regions of central and eastern Europe.

Jews who opted to stay in areas conquered by Christian armies or who chose to immigrate into western Christendom responded to the lure of economic opportunity. While the economic opportunity was real, the overall circumstances that greeted these Jews were, from many perspectives, daunting. They encountered a Church determined to limit them in multiple ways, political authorities for whom the immigrant Jews represented above all else a useful resource that might be heavily exploited and under certain circumstances jettisoned, and a populace that combined traditional Christian anti-Jewish thinking with normal antipathy toward newcomers. The Jewish experience in this rapidly developing area was both positive and negative. On the one hand, the Jews of medieval Christian Europe flourished demographically, economically, and culturally, in the process contributing in valuable ways to the general maturation of the European economy and system of governance and writing a new chapter in Jewish history; on the other hand, they suffered from Church limitations, governmental exploitation, and popular hostility and violence.