THE FOUR CALIPHS Following the death of the Prophet the first divisions appeared among the Muslims. No one could succeed Muhammad as a Prophet. Muhammad had designated no political successor though someone to guide the temporal affairs of the community was clearly needed. (This need was met through the appointment of his successors who came to be called Caliphs. (Arabic world meaning successor). The Caliphs had both spiritual and temporal authority. (Since there was no priesthood in Islam). However, the Caliphs had no authority in the matters of the religious doctrine which was available to the prophet. There were three main groups supporting rival contenders as successor of which Ali and Abu Bakr were the most important. Umar, who was to become the second caliph, was instrumental in getting a consensus in favour of Abu Bakr a senior companion of the Prophet. The decision over succession ' was taken according to tribal custom where a sayyid was chosen, not according to any formal democratic process but through a process of discussion and consent. The first four Caliphs had all been closely associated with Muhammad and are referred to the 'Rightly Guided' ones. Abu Bakr 632-34 A.D. Abu Bakr, as the first Caliph was mainly concerned with what have come to be known as wars against apostasy. Many of the tribes who had joined Muhammad, particularly those far from Medina felt that their alliance would be of little use now that Muhammad was dead. Abu Bakr had to reassert the authority of the ummah. There were six main areas of conflict. Interestingly, four of these were led by men claiming to be Prophets. Fighting occurred in many parts of Arabia and Abu Bakr succeeded in establishing the leadership of Medina all over the peninsula. Though these wars are referred to as ridda (apostasy) this was not always true. Many of the tribes who Abu Bakr fought had never accepted Islam. Muslim expansion had clearly begun. Outside the peninsular, in 633 A.D. a fortified Sassanian town near the Euphrates was taken and a Byzantine force was defeated in Southern Syria. Umar 634-44 A.D. It was during Umar's caliphate that most of the Fertile Crescent, Egypt, and much of Iran was conquered. It was also under him that the patterns of the government and finance of the Islamic regime were first worked out. The Arab World A man of tremendous energy, he was at first a violent opponent of Muhammad at Mecca, but once converted had become his great champion. His succession was uncontested. Islamic tradition however, has magnified his