In the summer or autumn of AD 661, Mu‘awiya b. Abi Sufyan, governor of Syria since 639 and already acclaimed by his Syrian followers as caliph (khalifa), religious and political leader of the Muslim state, entered the Iraqi garrison town of Kufa. In historical tradition this event is seen as bringing to an end a bitter period of civil war among the Arabs, achieving the reunification under one ruler of all the territories conquered by them, and initiating the caliphate of the Umayyad dynasty of which Mu‘awiya was the founder. The dynasty was to rule for 90 years or so until its overthrow and replacement by that of the ‘Abbasids in 749-50.