THE collapse of the Roman power in the East prepared the way for the Moslim conquest of Sinai and Egypt. During the lifetime of Mohammad changes were effected along peaceful lines. The efforts of the Prophet were directed, in the first place, against standing abuses and obsolete customs in Arabia itself. But the strong desire for expansion westwards among the Arabs drew his attention outside the limits of Arabia proper, and we hear of his entering into relation with neighbouring centres. Thus it is said that Tahhieh Ibn Robah of the port of Aila, waited on the Prophet when he was staying at Tarbuk, and that he received from him a woollen garment in return for paying a poll-tax. Ibn Ishak cited by Makrizi († 1441) stated that thus _firmân_ was dated to the ninth year of the Hegira, _i.e._ 530-531, and assured protection to Tahhieh, the people of Aila, the bishop and all on land and water. “And the city did not cease to prosper.”[212] The garment which Makrizi called a cloak of the Prophet, was subsequently purchased by the Caliph of the Benu el Abbas. Aila continued to flourish, and Mukaddisi (_c._ 985) described “Wailah” as “a populous and beautiful city among many palm trees with fish in plenty, and the great port of Palestine and emporium of the Hedjaz,” but the true Aila lies near by it and is now in ruins.[213] A later age claimed that the convent of Sinai also secured a _firmân_ under the hand of the Prophet. It was alleged that Mohammad, on one of his journeys with Ali, alighted under the wall of the convent, and that Ali penned the _firmân_, to which Mohammad, who could not write, set the mark of his blackened hand. The monks told Burckhardt that the Ottoman Sultan Selim, after the conquest of Egypt (A.D. 1517), appropriated it and carried it off to Constantinople, but that a copy of it remained with the monks. This he was shown, but declared it to be a forgery.[214] Bishop Pococke also saw another copy of it in Cairo, which he copied, and of which he published a translation in the appendix to his book. It claims to have been written in the second year of the Hegira, and granted protection to the Nazarenes, declaring that the places where the monks dwelt should be protected; also that they were exempt from paying the poll-tax, and should receive tithes, and that the Christians generally should not be called upon to pay a poll-tax exceeding ten drachmæ.[215] The followers of the Prophet, after overrunning Syria, attacked Egypt. They seized Damietta which was governed by Abu Thour, a Christian Arab, and were opposed by an army of 20,000 men. But Abu Thour was seized, and the invaders spread into Egypt. The descendants of Abbas, the uncle of the Prophet, now reigned over large possessions, of which Egypt was part, from the year 750 to 868. After a break the old line of rulers returned from 905 to 969.