Islam
Schism
There was another division within Islam, however; a religious division that appeared almost from the start and which continues to this day. This division would have a significant affect on Islamic history during the Crusades.
Muhammad died without naming a successor. After his death in 632, his followers gathered and discussed among themselves who should assume the mantle of leadership. None of these men claimed to be another prophet, only that the leadership of the faithful. Abu Bakr was chosen, but he died two years later. He was succeeded by Umar (634-644), who led the faithful to their most rapid and remarkable victories. On November 4, 644, Umar was at Medina, about to lead as imam in prayers. A captive Persian Christian (Persian had just been conquered) rushed forward and fatally stabbed Umar. As he lay dying, he appointed six men to decide who would succeed him.
The choice fell on Othman, a nobleman from Mecca. The other likely candidate was Ali, a cousin to the prophet and like Othman, one of the earliest converts, who was married to Fatima, Muhammad's daughter. I will not go into details here. Suffice it to say that Othman was murdered in 656 and three different men all claimed the succession, including Ali. A civil war ensued, during which Ali managed to win many adherents, but many enemies as well. He died in 661, likewise murdered. The party of Umar, led by Muawiya, was victorious, but the followers of Ali went into hiding and continued to adhere to his son, Husein.
Out of this civil war came the split between the Sunni and the Shi'ites. Sunni means the way or customs of the Prophet, a reference to the body of secondary literature that discussed the many aspects of life not directly dealt with in the Koran. The followers of Umar were Sunnites. Those who followed Ali were "Shi'a" and they claimed that the three caliphs who preceeded him (Abu Bakr, Umar, Othman) were all usurpers. Ali was the first, true caliph. The fundamental position of the Shi'ites was that succession after the Prophet must remain in the family of the Prophet (Ali was Muhammad's cousin). Outsiders could never be more than pretenders.
Since Ali's descendants were in hiding, tracing a line of authority became problematical. The result was, over time, a variety of competing claims emerged, splits within the ranks of the Shi'ites. Outwardly, they center on the question of the Imams (religious leaders), each group claiming a different founder. The Shi'ites have in common that they oppose Sunni dynasties, but the Shi'a is more of a variety of movements under one heading.
The most notable outward, political success of the Shi'ites came in 909 when Abu Abdallah produced a "hidden Imam" and proclaimed him Caliph. This marks the beginning of the Fatimid dynasty, which eventually was based at Cairo (969), though the Fatimids conquered much of North Africa as well. In the same century, the Buyids, a Persian clan that was also Shi'ite in loyalty, managed to take over the ailing Abassid caliphs in Baghdad. The Buyids never themselves claimed the caliphate, but their advent marks the high tide for the Shi'ites.
The situation in the 11th century, then, was that Islam was theoretically one community of the faithful, but in reality it was divided into several caliphates. Some of these were fierce rivals, others went their way independently. The caliphate of Egypt was Shi'ite, the one in Baghdad was controlled by Shi'ite viziers, and the rest were Sunni. None, except the far western ones, were strong in the 11th century.