But the arms of Persia did not long support the persecuting spirit of the Jews. The Emperor Heraclius, who had spent some inglorious years on the throne, was alarmed into activity by the progress of the enemy, who had threatened even the walls of Constantinople itself. The discipline of ancient Rome, which was not yet quite extinct among the legionary soldiers, maintained its wonted superiority over the less martial troops of Chosroes, and recovered in the course of a few campaigns all the provinces that the invaders had overrun. Heraclius visited Jerusalem as a pilgrim, when the wood of the true cross, which, it was rumoured, had been carried away to Persia, was reinstated with due solemnity. Several Christian churches, too, were restored to their former magnificence; and the law of Adrian was again put in force, which prohibited the Jews from approaching within three miles of the holy city.[168] Palestine continued to acknowledge the power of the emperor until the rise of Islamism changed the face of Western Asia. The armies of the califs, which wrested from Persia the dominion of the surrounding nations, conquered in succession the provinces of Arabia, Syria, and Egypt, and at length planted the crescent on the walls of Jerusalem. The victories of Omar in 636 decided the fate of the venerable city, and laid the foundations of a mosque on the sacred hill where the Temple of Solomon had stood. This conqueror was assassinated at Jerusalem in 643; after which, the establishment of several califates in Arabia and Syria, the fall of the Ommiades, and the elevation of the Abassides involved Judea in trouble for more than two hundred years. In 868, Achmet, a Turk, who from being governor had made himself sovereign of Egypt, conquered the capital of Palestine; but his son having been defeated by the califs of Bagdad; the holy city again returned under their dominion in the year 905 of our era. Mohammed Ikschid, another Turk, about thirty years after, having in his turn seized the throne of the Pharaohs, carried his arms into Palestine, and reduced the capital. The Fatimites, again, issuing from the sands of Cyrene, expelled the Ikschidites from Egypt in 968, and conquered several towns in Judea. Ortok, towards the end of the tenth century, made himself master of the holy city, whence his children were for a time driven out by Mostali, Calif of Egypt. In 1076, Meleschah, the third of the Turkish race, took Jerusalem, and ravaged the whole country. The Ortokides, who, as we have just related, were dispossessed by Mostali, returned thither, and maintained themselves in it against Redouan, Prince of Aleppo. They were expelled once more by the Fatimites, who were masters of the place when the crusaders first appeared on the confines of Syria.