Abu Bakr (632–4) and Umar (634–44) united the Arab tribes through successful campaigns of conquest, thereby strengthening Islam and preparing the way for it to become a world religion. In three decades the Arab conquerors took the Sasanian empire (Iraq and Iran) and the Byzantine territories of Syria, Egypt and northern Mesopotamia. The ‘city of the Prophet’, Medina, was the political centre of the empire; the garrisons of the armies of conquest became provincial centres. The indigenous governmental systems and the existing organisation of land ownership and taxation remained the basis for provincial administration.
The distribution of land and booty from the conquests produced social tensions. Misappropriation and economic exploitation of state funds by ÆUthmÅn (644–56) led to rebellion amongst the tribes. The crisis culminated after the murder of Uthman in the civil war against Imam Ali (656–61).
Amongst the opposition was the Shia of Imam Ali which fought for the rights of his immediate successors, the descendants of the Prophet, and the tribes of ‘secession’ (Kharijites), who claimed that theocracy had been betrayed.
Muhammad: the mission of the Arab Prophet
