At that time , Rav Gershom ben Judah was teaching at Metz and Mainz , gathering about him pupils from far and near . He is described in Jewish historiography as a model of wisdom , humility , and piety , and became known to succeeding generations as the " Light of the Exile " . In highlighting his role in the religious development of Jews in the German lands , '' The Jewish Encyclopedia '' ( 1901 – 1906 ) draws a direct connection to the great spiritual fortitude later shown by the Jewish communities in the era of the Crusades : He first stimulated the German Jews to study the treasures of their religious literature . This continuous study of the Torah and the Talmud produced such a devotion to Judaism that the Jews considered life without their religion not worth living ; but they did not realize this clearly until the time of the Crusades , when they were often compelled to choose between life and faith . The Jewish communities of the cities of Speyer , Worms , and Mainz formed the league of cities which became the center of Jewish life during Medieval times . These are referred to as the ShUM cities , after the first letters of the Hebrew names : Shin for Speyer ( '' Shpira '' ) , Waw for Worms ( '' Varmaisa '' ) and Mem for Mainz ( '' Magentza '' ) . The '' Takkanot Shum '' ( " Enactments of ShUM " ) were a set of decrees formulated and agreed upon over a period of decades by their Jewish community leaders . The official website for the city of Mainz states : Historian John Man describes Mainz as " the capital of European Jewry " , noting that Gershom ben Judah " was the first to bring copies of the Talmud to Western Europe " and that his directives " helped Jews adapt to European practices . " Gershom 's school attracted Jews from all over Europe , including the famous biblical scholar Rashi ; and " in the mid-14th century , it had the largest Jewish community in Europe : some 6,000 . " " In essence , " states the City of Mainz web site , " this was a golden age as area bishops protected the Jews resulting in increased trade and prosperity . " The First Crusade began an era of persecution of Jews in Germany , especially in the Rhineland . The communities of Trier , Worms , Mainz , and Cologne , were attacked . The Jewish community of Speyer was saved by the bishop , but 800 were slain in Worms . About 12,000 Jews are said to have perished in the Rhenish cities alone between May and July 1096 . Alleged crimes , like desecration of the host , ritual murder , poisoning of wells , and treason , brought hundreds to the stake and drove thousands into exile . Jews were alleged to have caused the inroads of the Mongols , though they suffered equally with the Christians . Jews suffered intense persecution during the Rintfleisch massacres of 1298 . In 1336 Jews from Alsace were subjected to massacres by the outlaws of Arnold von Uissigheim . When the Black Death swept over Europe in 1348 – 49 , some Christian communities accused Jews of poisoning wells . In the Erfurt Massacre of 1349 , the members of the entire Jewish community were murdered or expelled from the city , due to superstitions about the Black Death . Royal policy and public ambivalence towards Jews helped the persecuted Jews fleeing the German-speaking lands to form the foundations of what would become the largest Jewish community in Europe in what is now Poland/Ukraine/Romania / Belarus/Lithuania
Erfurt Massacre
Erfurt massacre (1349)
History of the Jews in Germany