When Muhammad died in 632, he left a political organization that was entirely centered around him. He was a political and military leader and he was the source of revelation. When political or social difficulties came up, not only would they center on Muhammad, but sometimes through revelation be mediated by Allah himself.
The central role of Muhammad left the growing Islamic polity with several difficulties. The first was the status of revelation itself—this became settled with the establishment of the definitive Qur'an . A more serious problem, though, involved the political and military succession to Muhammad. The only working model was an individual leader, but that leader had the authority of God behind him.
No-one seems to have thought very much about the succession to Muhammad before his death. No-one regarded Muhammad as divine or immortal, but no-one really considered what would happen after his death. The solution was cobbled together by the most powerful followers of Muhammad. There was disagreement—in fact, violent disagreement—between the Meccan followers of Muhammad who had emigrated with him in 622 (the Muhajirun, or "Emigrants") and the Medinans who had become followers (the Ansar, or "Helpers"). In the end, however, Muhammad's father-in-law, Abu Bakr, was named the khalifa or "Successor" of Muhammad. A new religion and a new circumstance had formed a new, untried political formation: the caliphate.
The Patriarchal Caliphs
The earliest caliphs were relatives and followers of Muhammad himself. Under these four caliphs, the political, social, and religious institutions of Islam would be solidified, including the definitive edition of the Qur'an.
The world of Islam would expand far beyond the borders of the Arabian peninsula during their tenure—east into the Persian empire, north into Byzantine territory, and west across the face of northern Africa.
Because of their foundational status and the fact that they were direct followers of Muhammad, these first four caliphs are called the patriarchs or patriarchal caliphs of Islam. For many Muslims, this was the golden age of Islamic government when a true Islamic polity was in existence; from some Muslims, such as Shi'ite Muslims, this was the only period when there was legitimate Islamic government. In this view, the founding of the Umayyad dynasty ushered in more than a millennium of illegitimate government.
Abu Bakr (632-634)
Abu Bakr, Muhammad's father-in-law and the father of Muhammad's most beloved wife, 'Aisha, was with Muhammad from the very beginning. Throughout the military campaigns with Mecca and later with other Arabian tribes, Abu Bakr had proven himself to be a military genius. Abu Bakr immediately called for a military expedition against the Byzantine empire, in part to revenge an earlier Islamic defeat and in part to focus Islamic and Arabian attention.
However, as soon as the Arabian tribes heard of the death of Muhammad, the Islamic peace and most of the alliances broke down. Several tribes revolted—some of these tribes revolted under the leadership of rival prophets. This began the period the Muslims call al-Ridda, or "The Apostasy." All of Abu Bakr's energy in the first years would be focussed on quelling these rebellions and tenuously re-establishing the Islamic peace.
Once the rebellions had been put down, Abu Bakr began a war of conquest. Whether or not he intended a full-out imperial conquest is hard to say; he did, however, set in motion a historical trajectory that in just a few short decades would lead to one of the largest empires in history. Abu Bakr began with Iraq, but before he could attack the Persian empire itself, he died—his death came only two years after he had been named the successor of Muhammad.
'Umar (634-644)
Abu Bakr desired 'Umar to be his successor and he persuaded the most powerful of the followers of Muhammad to go along. 'Umar was gifted both militarily and politically—it was his political genius above everything else that had helped to hold the Islamic world together during the life of Muhammad.
'Umar continued the war of conquests begun by Abu Bakr. He pressed into the Persian Empire itself, but he also headed north into Syria and Byzantine territory and west into Egypt. By 640, Islamic military campaigns had brought all of Mesopotamia and most of Syria and Palestineunder the control of Abu Bakr. Egypt was conquered by 642 and the Persian Empire by 643. These were some of the richest regions in the world guarded by powerful militaries—and they fell into Islamic hands in a heartbeat.
'Umar, however, was one of the great political geniuses of history. While the empire was expanding at a mind-numbing rate beneath his leaderhsip, he also began to build the political structure that would hold together the vast empire that was being built. 'Umar did not require that non-Muslim populations convert to Islam nor did he try to centralize government, as the Persians had done. Instead, he allowed subject populations to retain their religion, language, customs, and government relatively untouched. The only intrusion would be a governor (amir) and, sometimes, a financial officer called an 'amil, or agent.
His most far-reaching innovations were in the area of building a financial structure to the empire. He understood that the most important aspect of the empire was a stable financial structure for the government. To this end, he built an efficient system of taxation and brought the military directly under the financial control of the state. He also founded the diwan, a unique Islamic institution. The diwan consisted of individuals that were important to the Islamic faith and the Islamic world, such as the followers of Muhammad. Their contribution to the faith was so great that they were given pensions to live off of—this freed them up to pursue religious and ethical studies and so provide religious or ethical leadership to the rest of the Islamic world.
It was 'Umar that fixed many Islamic traditions and practices and he began the process of producing the Qur'an.
His most lasting tradition, however, was establishing the Muslim calendar. The Muslim calendar, like the Arabian calendar, remained a lunar calendar—however, he fixed the beginning of the calendar at the year in which Muhammad emigrated to Medina. This, as far as 'Umar was concerned, was the turning point in Islamic history.
'Uthman (644-656)
Nearing his death, 'Umar appointed a committee of six men to decide on the next caliph—they were charged to choose one of their own number. All of the men, like 'Umar, were from the tribe of Quraysh—the Ansar, or Medinans, had been gradually shut out of power.
This committee would prove to be pivotal, for on its choice would eventually grow Islam's first schism. The committee narrowed down the choices to two: 'Uthman and 'Ali. 'Ali was the son-in-law of Muhammad and had been a companion to the prophet from the inception of his mission. He may also have been named by Muhammad as a successor. "Uthman was an Umayyad, one of the wealthy clans that had bitterly opposed Muhammad. In fact, 'Uthman had started out opposed to Muhammad.
'Uthman, however, was a supremely practical and intelligent military and political leader while 'Ali was fervently devout religious disciple. 'Ali was largely convinced that Islam had gone astray and that it was not following either the religious, ethical, or social principles laid down in Muhammad's revelation. This profound difference between the two candidates led them to choose 'Uthman, for the growing Islamic empire seemed to need a practical, unreligious approach.
The decision was not a popular one. While 'Uthman reigned for twelve years as caliph, he met increasing opposition among both the original followers of Muhammad and among Islamic people in general. This opposition constellated around the figure of 'Ali who would, albeit briefly, succeed 'Uthman as caliph.
Despite internal troubles, 'Uthman continued the wars of conquest so brilliantly carried out by 'Umar. The Islamic empire conquered Libya in North Africa and fully conquered the eastern portions of the Persian Empire.
But unrest grew steadily and precipitously. His government seriously mishandled finances all throughout the empire. In 656, a riot broke out in Medina—so bitter were the rioters that they even threw stones at 'Uthman. The caliph called for military help. When the news of military reinforcements began to circulate among the rioters, they broke into 'Uthman's house and killed him while he was reading the Qur'an.
'Uthman's death was ironic for many reasons, including the fact that he was the first Islamic caliph or leader to be killed by fellow Muslims. But 'Uthman's greatest and most lasting achievement was the formal rescension of the Qur'an.
Until 'Uthman, the Qur'an was largely an oral text that was recited by followers who had memorized it. The wars of conquest, however, had thinned their ranks, and the introduction of foreign peoples into Islam threatened the integrity of the text as an Arabic text. So 'Uthman ordered that all versions, written and oral, be collected together and a definitive version written down. It is this definitive version which became the central text of Islam and the bedrock on which all Islamic history would be built. And it was this version, this brilliant achievement, that 'Uthman was reciting from when he was killed.