After Muhammad’s death, Muslim armies stormed out of Arabiaseeking to conquer other lands and thereby expand the dar al-Islam. Within a century after Muhammad’s death, Muslim armies had conqueredall of the Persian Empire and a good three-quarters of theChristian world. The new Islamic empire was ruled by caliphs, or successorsto Muhammad. Muhammad had no son, so the first caliphs were taken from hisinner circle of followers. The capital of the empire, therefore, remainedat Medina.All of these early caliphs were victims of assassination brought aboutby intrigue and fierce rivalry. A dispute arose concerning the nature of the caliphate, particularly after the elevation of Othman in 644 signaled a shift to the aristocracyof Mecca. Many argued that only one related by blood to Muhammadcould become caliph. A civil war broke out between supporters of Ali, a cousin and son-inlawof Muhammad, and those of the Umayyad family. By 661, the Umayyads had won, yet Ali’s supporters remained andcontinued to insist on his heirs’ true legitimacy. Those who supported Ali and his heirs were the Shiites, while thosewho did not were the Sunni. Both sides would remain hostile toeach other. The Umayyads moved the capital to Damascus, which was more centrally located. Power in the empire was increasingly based on Arab identity rather than simply Islamic faith. Arabs often remained separate from local populations and conversions were even discouraged. Yet conversions occurred nonetheless. Non-Arab Muslims, or mawali,were actively discriminated against, yet they continued to rise in powerand prominence. The mawali helped to overthrow the Umayyads, ushering in the new Abbasid caliphate in 750. The basis of power was once again the Islamic faith. The capital was moved to Baghdad and the caliphs adopted aPersian/Byzantine style of rulership. Although in theory the dar al-Islam or umma (community of all Muslims)was one, in reality it split into competing caliphates and emirates.