Christian and Jewish communities who had submitted to Muslim rule were allowed to worship in their own way and follow their own family law, and were given a degree of self-government. However, the non-Muslim were subject to taxation (known as ) at a different rate to the Muslim . also faced economic impediments, restrictions on political participation and/or social advancement based on their non-Muslim status. Some Jews generally rejected Muhammad's status as a prophet. According to Watt, "Jews would normally be unwilling to admit that a non-Jew could be a prophet." In the Constitution of Medina, Muhammad demanded the Jews' political loyalty in return for religious and cultural autonomy. In every major battle with the Medinans, two local Jewish tribes were found to be treacherous (see ). After Badr and Uhud, the Banu Qainuqa and Banu Nadir (the latter being an ethnic Arab tribe who converted to Judaism, according to the Muslim historian al-Yaqubi), respectively, took up arms against the ummah and were subsequently expelled "with their families and possessions" from Medina. However, this incident does not imply that Jews in general rejected Muhammad's constitution. One Yemenite Jewish document, found in the Cairo Genizah, claims that many Jews had not only accepted Muhammad as a prophet, but even desecrated Sabbath in order to join Muhammad in his struggle; historians suggest that this document, called (Muhammad's Writ of Protection), may have been fabricated by Yemenite Jews for the purpose of self-defence. Still, some Yemeni Jews considered Muhammad a true prophet, including Natan'el al-Fayyumi, a major 12th century rabbi who incorporated various Shia doctrines into his view of Judaism. The Syriac Patriarch Ishôyahb III wrote in his correspondence to Simeon of Rewardashir, "As for the Arabs, to whom God has at this time given rule (shultãnâ) over the world, you know well how they act toward us. Not only do they not oppose Christianity, but they praise our faith, honour the priests and saints of our Lord, and give aid to the churches and monasteries." After Muhammad's death in 632, Islamic rule grew rapidly, encompassing what is now the Middle East, Egypt, North Africa, and Iran. Most of the new subjects were Christian, Jewish, and Zoroastrian, the first two being considered People of the Book. (After some argument, the Zoroastrians were considered People of the Book as well.) Christians, Jews, and Zoroastrians were called , protected persons. As noted above, they could