Bosra played an important part in the early life of Muhammad (?), as described in the entry for the Christian monk Bahira. The forces of the Rashidun Caliphate under general Khalid ibn Walid captured the city from the Byzantines in the Battle of Bosra in 634. Throughout Islamic rule, Bosra would serve as the southernmost outpost of Damascus, its prosperity being mostly contingent on the political importance of that city. Bosra held additional significance as a center of the pilgrim caravan between Damascus and the Muslim holy cities of Mecca and Medina, the destinations of the annual "hajj" pilgrimage. Early Islamic rule did not alter the general architecture of Bosra, with only two structures dating to the Umayyad era (721 and 746) when Damascus was the capital of the Caliphate. As Bosra's inhabitants gradually converted to Islam the Roman-era holy sites were utilized for Muslim practices. In the 9th-century Ya'qubi wrote that Bosra was the capital of the Hauran province.