Rise of Islam
The conquest of large territories resulted in destruction of the caliphate based in Medina. In due course of time, an increasingly authoritarian polity took over. To consolidate their leadership within the umma, the Umayyads implemented a series of political measures. Muawiya, who was the first Umayyad caliph, moved his capital to Damascus. He adopted the court ceremonies and administrative institutions of the Byzantine Empire. He introduced hereditary succession. This innovation enabled the Umayyads to retain power for 90 years. In similar manner, the Abbasids ruled for two centuries.
The Umayyad state became an imperial power which was no longer based directly on Islam but on statecraft and loyalty of Syrian troops. There were Christian advisers, and Zoroastrian scribes and bureaucrats in the administration. But Islam continued to provide legitimacy to their rule. They always appealed for unity and suppressed rebellion in the name of Islam.
Emphasis on Arabic and Islamic Identities: During the reign of Abd al-Malik (685-705) and his successors, both the Arab and Islamic identities were strongly emphasized. Abd al-Malik adopted Arabic as the language of administration and introduced Islamic coinage. Coins (denarius and drachm) of Byzantine and Iran were copied to introduce the gold dinar and silver dirham. Symbols of crosses and fire altars and Greek and Pahlavi inscriptions were replaced with Arabic inscriptions. The Dome of the Rock was built in Jerusalem to create a highly visible Arab-Islamic identity.
The Abbasid Revolution
The Abbasids started a well-organised movement, called dawa, that brought down the Umayyad rule in 750. The Abbasid uprising broke out in Khurasan (eastern Iran). Khurasan had a mixed Arab-Iranian population. The Arab soldiers in Khurasan were mostly from Iraq and resented the dominance of the Syrians. The Umayyad regime had made promises of tax concessions and privileges but never fulfilled those promises. This created resentment among the civilian Arabs of Khurasan. The Iranian Muslims (mawali) were subjected to the scorn of the race-conscious Arabs. The Abbasids were the descendants of Abbas who was the Prophet’s uncle. They mustered the support of various dissident groups. The Abbasids legitimized their bid for power by promising that a messiah (mahdi) from the family of the Prophet would liberate them from the oppressive Umayyad regime. The Abbasid army was led by an Iranian slave, Abu Muslim. He defeated the last Umayyad caliph, Marwan, in a battle at the river Zab.
The Arab influence declined and the Iranian influence increased under the Abbasid rule. The new capital was established at Baghdad, near the ruins of the ancient Iranian metropolis, Ctesiphon. In order to ensure greater participation by Iraq and Khurasan, the army and bureaucracy were reorganized on a non-tribal basis. Islam was patronized and the religious status and functions of the caliphate was strengthened. But the Abbasids were forced to retain the centralized nature of the state. They also maintained the magnificent imperial architecture and elaborate court ceremonials of the Umayyads.