The Arab–Byzantine Wars Wars, a series of wars between Arab Caliphates and the Byzantine Empire between the 7th and 12th centuries CE, start during the initial Muslim conquests under the Rashidun and Umayyad caliphs and continue in the form of an enduring border tussle until the mid-11th century.

As result the Byzantines, also called the Romans ("Rûm" in Muslim historical chronicles; the Byzantine Empire was formerly the Eastern half of the Roman Empire), see an extensive loss of territory.The eruption of the Arabs from the Arab Peninsula in the 630s results in the rapid loss of Byzantium's southern provinces (Syria and Egypt) to the Muslims.

Over the next fifty years, under the aggressive Umayyad caliphs, the Muslims launch repeated raids into still-Byzantine Asia Minor, twice threaten the Byzantine capital, Constantinople, with conquest, and outright conquer the Byzantine Exarchate of Africa.

The situation does not stabilize until after the failure of the Second Arab Siege of Constantinople in 718, when the Taurus Mountains on the eastern rim of Asia Minor became established as the mutual, heavily fortified and largely depopulated frontier.

Under the Abbasid Empire, relations became more normal, with embassies exchanged and even periods of truce, but conflict remained the norm, with almost annual raids and counter-raids, sponsored either by the Abbasid government or by local rulers, well into the 10th century.During the first centuries, the Byzantines are usually in the defensive, and avoid open field battles, preferring to retreat to their fortified strongholds.

Only after 740 do they begin to launch counterstrikes of their own, but still the Abbasid Empire is able to retaliate by often massive and destructive invasions of Asia Minor.

The occupation of southern Italian territories by the Abbassid forces occurs in the 9th and 10th centuries.

With the decline and fragmentation of the Abbasid state after 861 and the concurrent strengthening of the Byzantine Empire under the Macedonian dynasty, the tide gradually turns.

Over a period of fifty years from ca.

920 to 976, the Byzantines finally break through the Muslim defenses and restore their control over northern Syria and Greater Armenia.

The Muslims also take to the sea, and from the 650s on, the entire Mediterranean Sea becomes a battleground, with raids and counter-raids being launched against islands and the coastal settlements.

Muslim raids reach a peak in the 9th and early 10th centuries, after their conquest of Crete, Malta and Sicily, with their fleets reaching the coasts of France, Dalmatia and even the suburbs of Constantinople.The last century of the Byzantine-Arab wars is dominated by frontier conflicts with the Fatimids in Syria, but the border remains stable until the appearance of a new people, the Seljuk Turks, after 1060.

The Emirate of Aleppo and its neighbors become vassals of the Byzantines in the east, where the greatest threat is the Egyptian Fatimid kingdom, until the rise of the Seljuk dynasty reverse all gains and pushes Abbassid territorial gains deep into Anatolia.

This results in the Byzantine emperor Alexius I Comnenus' request for military aid from Pope Urban II at the Council of Piacenza; one of the events often attributed as precursors to the First Crusade.