Sect Formation After Muhammad’s death in , no one could legitimately claim to be the next prophet of Islam. As a result, his political authority was transferred to the umma with no established principle of succession. This created opportunities for innovations but also caused deep divisions among the Muslims. The biggest innovation was the creation of the institution of caliphate, in which the leader of the community ( amir al- muminin ) became the deputy ( khalifa ) of the Prophet.
The first four caliphs ( - ) justified their powers on the basis of their close association with the Prophet and continued his work under the general guidelines he had provided. The twin objectives of the caliphate were to retain control over the tribes constituting the umma and to raise resources for the state. Following Muhammad’s death, many tribes broke away from the Islamic state. Some even raised their own prophets to establish communities modelled on the umma .
The first caliph, Abu Bakr, suppressed the revolts by a series of campaigns. The second caliph, Umar, shaped the umma’s policy of expansion of power. The caliph knew that the umma could not be maintained out of the modest income derived from trade and taxes. Realising that rich booty ( ghanima ) could be obtained from expeditionary raids, the caliph and his military commanders mustered their tribal strength to conquer lands belonging to the Byzantine Empire in the west and the Sasanian empire in the east.
At the height of their power, the Byzantine and Sasanian empires ruled vast territories and commanded huge resources to pursue their political and commercial interests in Arabia. The Byzantine Empire promoted Christianity and the Sasanian empire patronised Zoroastrianism, the ancient religion of Iran. On the eve of the Arab invasions, these two empires had declined in strength due to religious conflicts and revolts by the aristocracy. This made it T HE C ENTRAL I SLAMIC L ANDS T HEMES IN W ORLD H ISTORY easier for the Arabs to annex territories through wars and treaties.
In three successful campaigns ( - ), the Arabs brought Syria, Iraq,