Within only a few years after the death of Mohammed in 632, the military consequences of the rise of Islam began to emerge. Saracens, as the followers of Islam were known in Europe at that time, seized the Arabian fortress outpost of the Byzantine [Eastern Roman] Empire in 634. By 643 they had control of Syria and most of Egypt. By the end of the century Saracen conquests had expanded to include Persia and Armenia in the east and all of North Africa in the west. Even Constantinople itself, the capital of the Byzantine Empire, was besieged by Saracen forces in 673-7 and again in 717-8, though in each case the attacks were repulsed.

From North Africa the Saracens burst into Europe by seizing Iberia [present-day Spain and Portugal], where Roman rule had been replaced by a succession of Vandals, Suevi, Alans and finally Visigoths. In 718 Saracen forces struck across the Pyrenees into present-day France. Finally, their advance was halted and decisively repelled by Charles Martel and his Frankish army at the Battle of Poitiers in 732--one of the most influential battles in European history.

Sicily was still a possession of the Byzantine Empire but, as a crossroads between Africa, Asia and Europe, it could not expect to be untouched by the broad clashes that surrounded it. Saracen attacks on the island began at least as early as 655, with a strong raid from Damascus in Syria. Later, Syracuse was sacked by Saracens from Alexandria in Egypt. In 827 Saracens from North Africa began a determined invasion of the island. Over the next two years, Agrigento and several smaller cities fell to the invaders, but attacks on Syracuse and Enna failed.

In fact, the fall of Byzantine Sicily came not from Asia or Africa, but from Europe itself.