In the early Islamic period, Homs (in Arabic: "Ḥimṣ") was one of the chief cities of the province of Syria, being the capital of one of its five military districts during the era of the Umayyad Caliphate (661–750). After the Syrian-based Umayyads were replaced by the Iraq-centric Abbasids, however, the city entered a turbulent period, in which tribal factionalism and the ambitions of the local "ashraf" triggered regular outbreaks of disorder. Beginning in the reign of Harun al-Rashid (786–809), the central government was compelled to send numerous punitive expeditions against Homs and its vicinity, and the city's reputation for rebellion became even greater following the end of the Fourth Civil War in Syria (c. 825). As a result of these activities, the city gradually became known as the dominant arena for unrest in the region, a status which peaked in the middle of the ninth century.