How far these conquests would have continued it is difficult to say had not Genesric died. With his death his followers, who had drifted into an easy-going state, no longer held together, but became the prey of jealous strifes among chiefs. Their fall was rapid. The Roman Government, now transferred to Constantinople, was awaiting the opportunity to avenge its defeat. A little more than a hundred years after the landing of the Vandals in Africa, Belisarius sailed from Constantinople with six hundred ships, and three months later landed in Tripoli.

The Byzantine invasion had begun, and in three months Belisarius was able to announce to the Emperor Justinian that North Africa was again part of the Roman Empire.

But the Byzantine rule did not last long. The country was rent by wars and revolts; the people were worn out with changes of government; and, though there remain great forts and mightily walled cities as a record of this rule, they are evidence in themselves of the turbulent times which shook the country. When, therefore, the first Arab invasion poured in, there was nothing to quell it, and for one last time Imperial Rome struggled for a moment, staggered and fell.

The first Arab invasion of the seventh century was more a series of raids than anything else. Mohammed had appeared and died, but his teaching had remained, and had inspired those bands of wild nomads to organize themselves. Persia, Syria, Egypt had fallen before the advance, and soon they began moving farther west. The most important of these raids was that led by Sidi Okba, who traversed the whole of Algeria and Morocco, and who, no doubt, would have gone on had he not been arrested by the Atlantic.

He was killed during his return journey by the Berber army under Koceila, and he is buried near Biskra, where his memory is venerated.

Hassan followed him, and finally drove the last Byzantines out of North Africa. Needless to say, the chief object of the invaders had been to convert the people to the new faith, and little by little the Berbers became Mohammedans. It did not take long for them to create dissension in these beliefs, but they remained generally under the law of the Prophet, respecting the principles even more rigidly than their conquerors.

However, the most important point of this conversion is that it created an Arab-Berber alliance for the further march of Mohammedanism into Europe. It is said that it was a Berber named Tarik who first crossed the Straits of Gibraltar, and it was after him that the rock took its name, Djebel el Tarik—the Mountain of Tarik.

The Arabs and Berbers pressed on through Spain until they were defeated by Charles Martel at Poitiers in 732 and retired into the peninsula. The remains of their grandeur can be seen in the glorious palaces and mosques at Seville, Cordova and Granada. But the Berbers, being of an independent nature, did not readily accept the laws and regulations of the allies. In the tenth century there were a number of insurrections in Algeria, and the Fatimides, or followers of the descendant of Fathma, the daughter of the prophet, succeeded for a period in dominating the country. Unfortunately for them their chief tried to go too far in his independence, and in the twelfth century the Sultan at Cairo launched a punitive expedition composed of the five tribes known as the Hilals.

Unlike the expeditions of the seventh century, these invaders came in hordes, bringing with them their flocks and their belongings, and sweeping mercilessly across the country, leaving devastation behind. Arabs and Berbers united to oppose them, but to no avail. Their armies poured over the land like a cloud of locusts. The little that was left of Roman civilization was destroyed, the cultivation disappeared, and North Africa was the desert of over a thousand years before.

From this period until the end of the fifteenth century North Africa was given over to pillage. With the exception of the cities of Tunis, Tlemçen and Fez, anarchy seems to have reigned everywhere, and there are no records or history of the period. The Arab had shown his worth; the Arab as an administrator had no qualification; he has not yet proved the contrary.