Introduction After the death of Muhammad, the Muslim community convened a meeting at Saqifah. The outcome of the meeting was the election of Abu Bark as the caliph. Quite a number of Muhammad’s cohorts rowed this preference asserting that his cousin and son-in-law were the elected descendants. In fact, the Muslim population shortly separated into nearly four camps in the foremost and subsequent Fitna. This paper argues that Sunni and Shia Muslims had different ideas about successorship which shaped the leadership of the caliphs. It attempts to answer the question; “what kinds of arguments, methods and policies did the Rashidun, Umayyad, Abbasid and Fatimid caliphs/imams (and their defenders) use to legitimize their claims of political and religious authority?” Rows over Muhammad succession Basically, from a spiritual standpoint, Muslims separated into two parties namely the Shia and the Sunni. The Sunnis alleged that while Muhammad failed to choose a descendant, Abu Bark was nominated as the first caliph by the Muslim society. They identified the first four caliphs under Rashidun caliphate as the rightful successors of Muhammad. Shias emphasized that Muhammad overtly forenamed Ali as the heir at Ghadir Khumm and Muslim headship was accorded to the person who had been appointed by Allah. Moreover, the Sunni and Shia disagreed on the feelings of Ali towards Rashidun caliphate (Dale 33). Sunnis underlined his reception and support for Rashidun caliphate, whereas Shia averred that he reserved himself from such a ruling. They further claim that Ali was kept from accomplishing the religious responsibility that Muhammad had assigned to him. Sunnis also argue that if Ali was the divine successor, then it would have been his role as a Muslim leader to fight the wrong leadership until he established a ruling. Shia maintains that Ali failed to make war because he lacked the military strength yet if he fought, it would have triggered a civil war among the Muslims. Methods used to legitimize authority As noted earlier, the caliphates or dynasties that followed the death of Muhammad worked under the viewpoints of either Sunni or Shia Muslims. One method used by caliphs to legitimize political authority was the initiation of military action. Beginning from Rashidun dynasty to Fitimid dynasty, military congests were major determinants of authority (Dale 39). A particular caliph could claim the position due to the military success of the former caliphs in his lineage. Another method that caliphs legitimized their religious authority was through welfare works. The faithful used mosques as places for worship as well as community centers, where they met to discuss societal issues (Lindsay, 100). The respect a caliphate got was equivalent to the number of mosques he constructed. For example, all through Umar caliphate, the caliphs built thousands of mosques stretching across the entire Islamic region; from Persia to Egypt. This reflected the immense influence. Policies used to legitimize authority The authority exercised by caliphs was based on policies created through varying views of sharia. Sunni Muslims held the belief that the caliphs were earthly rulers, chosen by the community to rule withi