Tenuous Byzantine control over Libya was restricted to a few poorly defended coastal strongholds, and as such, the Arab horsemen who first crossed into the Pentapolis of Cyrenaica in September 643 CE encountered little resistance. Under the command of 'Amr ibn al-'As, the armies of Islam conquered Cyrenaica, and renamed the Pentapolis, Barqa. They took also Tripoli, but after destroying the Roman walls of the city and getting a tribute they withdrew. In 647 an army of 40,000 Arabs, led by Abdullah ibn Saad, the foster-brother of Caliph Uthman, penetrated deep into Western Libya and took Tripoli from the Byzantines definitively. From Barqa, the Fezzan (Libya's Southern region) was conquered by Uqba ibn Nafi in 663 and Berber resistance was overcome. During the following centuries Libya came under the rule of several Islamic dynasties, under various levels of autonomy from Ummayad, Abbasid and Fatimid caliphates of the time. Arab rule was easily imposed in the coastal farming areas and on the towns, which prospered again under Arab patronage. Townsmen valued the security that permitted them to practice their commerce and trade in peace, while the Punicized farmers recognized their affinity with the Semitic Arabs to whom they looked to protect their lands. In Cyrenaica, Monophysite adherents of the Coptic Church had welcomed the Muslim Arabs as liberators from Byzantine oppression. The Berber tribes of the hinterland accepted Islam, however they resisted Arab political rule.