_The Rise and Expansion of the Arabian Empire_.--Mohammedanism, which arose in the beginning of the seventh century, spread rapidly over the East and through northern Africa, and extended into Spain. All Arabia was converted to the Koran, and Persia and Egypt soon after came under its influence. In the period 623-640, Syria was conquered by the Mohammedans, upper Asia in 707, and Spain in 711. They established a great caliphate, extending from beyond the Euphrates through Egypt and northern Africa to the Pyrenees in Spain. They burned the great library at Alexandria, founded by Ptolemy, destroying the manuscripts and books in a relentless zeal to blot out all vestiges of Christian learning. In their passage westward they mingled with the Moors of northern Africa, whom they had subdued after various struggles, the last one ending in 709. In this year they crossed the Strait of Gibraltar and encountered the barbarians of the north. The Visigothic monarchy was in a ruined condition. Frequent internal quarrels had led to the dismemberment of the government and the decay of all fortifications, hence there was little organized resistance to the incoming of the Arabs. All Spain, except in the far north in the mountains of the Asturias, was quickly reduced to the sway of the Arabs. They crossed the Pyrenees, and the broad territory of Gaul opened before them, awaiting their conquest. But on the plains between Tours and Poitiers they met Charles Martel with a strong army, who turned the tide of invasion back upon itself and set the limits of Mohammedan dominion in Europe. In the tenth century the great Arabian Empire began to disintegrate. One after another of the great caliphates declined. The caliphate of Bagdad, which had existed so long in Oriental splendor, was first dismembered by the loss of Africa. The fatimate caliphate of northern Africa next lost its power, {306} and the caliphate of Cordova, in Spain, brilliant in its ascendancy, followed the course of the other two. The Arabian conquest of Spain left the country in a state of tolerable freedom, but Cordova, like the others, was doomed to be destroyed by anarchy and confusion. All the principal cities became in the early part of the eleventh century independent principalities.