The Arab–Byzantine wars or Muslim–Byzantine wars were a series of wars from the 7th to 11th centuries between multiple Arab dynasties and the Byzantine Empire. The Muslim Arab Caliphates conquered large parts of the Christian Byzantine empire and unsuccessfully attacked the Byzantine capital of Constantinople. The frontier between the warring states remained almost static for three centuries of frequent warfare, before the Byzantines were able to recapture some of the lost territory.
The conflicts began during the early Muslim conquests under the expansionist Rashidun Caliphate, part of the initial spread of Islam. In the 630s, Rashidun forces from Arabia attacked and quickly overran Byzantium's southern provinces. Syria was captured in 639 and Egypt was conquered in 642. The Exarchate of Africa was gradually captured between 647 and 670. From the 650s onwards, Arab navies entered the Mediterranean Sea, which became a major battleground. Both sides launched raids and counterraids against islands and coastal settlements. The Rashidun were succeeded by the Umayyad Caliphate in 661, who over the next fifty years captured Byzantine Cyrenaica and launched repeated raids into Byzantine Asia Minor. Umayyad forces twice placed Constantinople under siege, in 674 to 678 and 717 to 718, but failed to seize the heavily fortified Byzantine capital.