In 644, al-'Ala' ibn al-Hadrami, the Rashidun governor of Bahrain, once again attacked Fars, reaching as far as Estakhr, until he was repelled by the governor (marzban) of Fars, Shahrak.[lower-alpha 1] Some time later, Uthman ibn Abi al-As managed to establish at Tawwaj a Misr, a military base whose regimental system was based on the Immigrant Tribal (mainly Arabs) system, and shortly defeated and killed Shahrak near Rew-shahr (however other sources state that it was his brother who did it). A Persian convert to Islam, Hormuz ibn Hayyan al-'Abdi, was shortly sent by Uthman ibn Abi al-'As to attack a fortress known as Senez on the coast of Fars. After the accession of Uthman ibn Affan as the new Caliph of the Rashidun Caliphate on 11 November 644, the inhabitants of Bishapur, under the leadership of Shahrak's brother, declared independence, but were defeated.[lower-alpha 2]