No feature of the history of the eighth century is so remarkable as the genesis and explosive growth of the world of Islam. There was literally no precedent for it in antiquity and no reason why a reasonable, contemporary observer should have expected it. In scarcely two decades from the death of Muhammad in 632 a newly united Arab world had swept away the Persian Empire of the Sassanids and was probing the valley of the Indus in the east. The same period had seen it tear the provinces of Syria, Palestine, and Egypt, from the Byzantine Empire and for more than a century yet the ultimate survival of the Eastern Roman Empire was open to serious doubt.

That the initial energies of Islam were far from spent meant that expansion to the west in Africa after the fall of Egypt in 642 was in the natural order of things. That northern coast had long been an important part of the Roman world, the Byzantine enemy was still entrenched there, and the climate and geography were congenial to the Arab. After a series of exploratory thrusts and counterthrusts, the great Byzantine capital and base at Carthage fell definitively in 698. The major problem to Arab rule in the African northwest now became the resistance of the native Berber peoples of the region. But in fairly short order there, Islam was to demonstrate its remarkable absorptive power for unsophisticated peoples.