How did medieval societies treat neighbours who worshipped another god? In Latin Christendom the answer swung between protection and expulsion. After the First Crusade, in which more than five thousand Jews were killed in 1096, Pope Callixtus II issued the bull Sicut Judaeis around 1120, forbidding forced conversion and violence against Jews. Yet in 1215 the Fourth Lateran Council required Jews and Muslims to wear distinctive clothing, England expelled its Jews in 1290, and Spain's Alhambra Decree of 1492 drove out tens of thousands more. In the Islamic world, Jews and Christians — the “People of the Book” — became dhimmis, “protected people”: they paid the jizya tax and in return kept their lives, property, places of worship and their own courts, though they lived under restrictions and could not hold the highest offices. A Jewish physician, Hasdai ibn Shaprut, served as the Caliph of Córdoba's trusted diplomat in the tenth century; yet in Cairo the caliph al-Hakim ordered churches and synagogues demolished around 1012, before his successor let them be rebuilt. In China, foreign faiths depended on the emperor's will. The Tang emperor Taizong welcomed Syriac Christian missionaries in 635, and a stele of 781 still records their history; but in 845 Emperor Wuzong destroyed more than 4,600 Buddhist monasteries and forced over 3,000 Christian and Zoroastrian clergy back to lay life. Persecution, protection and permission: three ways of living with difference — none of them yet equality.