Under the leadership of Emir Assaf, they were confirmed as the rulers of Keserwan by Sultan Selim I following the Ottoman conquest in 1516. Emir Assaf died two years later and was succeeded by his son Hasan, who was in turn killed by his brother Qa'itbay. The latter ruled Keserwan until his death without children in 1523, after which he was succeeded by Hasan's son Mansur. Mansur had a long reign and was accorded by the Ottomans numerous districts in Mount Lebanon and its environs as tax farms. He eliminated many of his Sunni rivals, and his local power relied on a Maronite Christian support base and his Maronite agents, namely members of the Hubaysh clan, who served as a check on the Shia Muslim sheikhs of Keserwan. At the peak of his power, Mansur's realm stretched from Beirut to Homs.