Soon after, al-Mahdi appointed Ibn Abi Khinzir as his first governor in Sicily, which the Aghlabids had largely conquered from the Byzantine Empire.[7] He was accompanied by his brother Ali and the new chief qadi for the island, Ishaq ibn Abi Minhal, as well as a new official, the "Lord of the Fifth" (sahib al-khums), who was sent to collect one fifth of all income according to Shi'a juridical traditions—something which the Sunni and fiercely independent-minded Arab–Berber Sicilian warrior caste vehemently opposed.[5][8] The new governor arrived at Mazara on 20 August 910, and made for the island's capital, Palermo, while leaving his brother at Agrigento, which was held by a strong Berber garrison.[8] In the summer of 911, Ibn Abi Khinzir led the customary annual raiding campaign against the remaining Byzantine strongholds in the northeast (the Val Demone).