The Byzantines hardly overcame the Perse that a new enemy presents himself to the borders. The year 622 where Héraclius launched its offensive against Persia is also remembered by the beginning of the Hégire. Eleven years later the expansion from the Arab conquests begins.

Héraclius immediately does not take the threat with the serious one. But after some defeats, its army is massacred in 636 with the Bataille of Yarmouk by that of the caliph Omar, who takes the control of the Syria the same year. In 638, Buckwheats take Jerusalem following a long seat, in 640 fix the Arménie and the west of the Anatolia, and in 642 seize the Egypt which is definitively lost for the empire. The Exarchat of Carthage is plundered in 647 and will disappear in 698, which will give to Buckwheats the control of all the North-African littoral. The war against Persians was finally used for nothing.

Now main on Syria and Egypt, the Arabs decide, from 644, to build a military fleet. Ten years later, they seize the Crete, Rhodos and Cos, along the Anatolian littoral. Then in 655 takes place the first great naval battle between the Byzantines and the Arabs. The Roman fleet is destroyed with broad of Finike. Lastly, in 674 starts the head office of Constantinople with the sea route.

But new the basileus Constantin IV has a secret weapon which will henceforth ensure the domination to him on the Arabs: the Greek fire. After five years of seat, which sees being consumed the fleet of the caliph Mu `âwiya, this one accepts finally the restitution of all the islands of the Mediterranean, as well as the payment of a tribute (678). In 717, it ordering Maslama, wire of the caliph `Abd Al-Malik, passes by again with the offensive and establishes this time a total blockade around Constantinople. But Leon III known as Isaurien had time to prepare and the seat is pushed back the following year with the support of the Bulgare S.

It will be necessary to await the end of the dynasty of the Omeyyades in 750 so that the Arabs do not represent any more a danger to the empire. To this date, the new dynasty of the Abbassides transfers its capital from Damas to Baghdad and turns now to Persia. In 838, the caliph Al-Mutasim will advance well his army until Amorium in Anatolia, but its death will put an end to military operation. Under the Abbasids, the war continues but does not concern any more that the borders, it will concentrate in particular on the Sicily, Crete.

See too

Internal bonds

• History of Sardinia