Berber Zirid dynasty for having abandoned Shiism. The Banu Hilal reduced the Zirids to a few coastal towns and took over much of the plains, resulting in the spread of nomadism to areas where agriculture had previously been dominant. Besides the Arabian influence, North Africa also saw an influx, via the Barbary slave trade, of Europeans, with some estimates placing the number of European slaves brought to North Africa during the Ottoman period to be as high as 1.25 million. Interactions with neighboring Sudanic empires, traders, and nomads from other parts of Africa also left impressions upon the Berber people. Islamic conquest The first Arabian military expeditions into the Maghreb, between 642 and 669, resulted in the spread of Islam. These early forays from a base in Egypt occurred under local initiative rather than under orders from the central caliphate. But when the seat of the caliphate moved from Medina to Damascus, the Umayyads (a Muslim dynasty ruling from 661 to 750) recognized that the strategic necessity of dominating the Mediterranean dictated a concerted military effort on the North African front. In 670, therefore, an Arab army under Uqba ibn Nafi established the town of Qayrawan about 160 kilometres south of modern Tunis and used it as a base for further operations. Abu al-Muhajir Dinar, Uqba's successor, pushed westward into Algeria and eventually worked out a modus vivendi with Kusaila, the ruler of an extensive confederation of Christian Berbers. Kusaila, who had been based in Tlemcen, became a Muslim and moved his headquarters to Takirwan, near Al Qayrawan. This harmony was short-lived; Arabian and Berber forces controlled the region in turn until 697. Umayyad forces conquered Carthage in 698, expelling the Byzantines, and in 703 decisively defeated Dihya's Berber coalition at the Battle of Tabarka. By 711, Umayyad forces helped by Berber converts to Islam had conquered all of North Africa. Governors appointed by the Umayyad caliphs ruled from Kairouan, capital of the new wilaya (province) of Ifriqiya, which covered Tripolitania (the western part of modern Libya), Tunisia, and eastern Algeria. The spread of Islam among the Berbers did not guarantee their support for the Arab-dominated caliphate, due to the discriminatory attitude of the Arabs. The ruling Arabs alienated the Berbers by taxing them heavily, treating converts as second-class Muslims, and, worst of all, by enslaving them. As a result, widespread opposition took the form of open revolt in 739–740