After the death of El Mâmûn, the seventh of the ’Abbaside khalifs, the Arab empire began to crumble away. In his reign Crete and Sicily were conquered, and the power of Islâm extended to the borders of India. But the simple creed of Muḥammad was undermined by philosophy, scepticism, and mysticism in the East, while the Turkish mercenaries who guarded the khalîfah at Baghdâd soon became his masters. To the Turk the civilisation and philosophy of the age were of little value. He understood the Ḳorân, and became a fanatical Moslem on conversion; his influence was reactionary, and where he ruled, civilisation made little progress. Revolts in the provinces were frequent, and the khalifs became mere religious figure-heads. One of the first secret sects in Islâm appeared near Merv in 767 A. D., where El Moḳann’a, the “veiled” prophet, was joined by the Turks. A yet more formidable society was that of El Ḳarmat of Ḳûfa, appearing in 890 A. D. The Ḳarmathians pillaged Mekkah in 929 A. D., and their secret scepticism with exoteric mysticism was the origin of later Druze heresies which affected the history of Jerusalem. For two centuries the power of the Turks continued to increase in the East till Togrul entered Baghdâd in 1055 A. D. In the West also the employment of Turks as governors led to the disruption of the Arab empire. Ibn Tulûn in Egypt renounced fealty to the khalîfah in 868 A. D., and his family reigned in Syria till 905 A. D. Again in 934 A. D. Ikshîd--also a Turk--revolted, and his successors held Egypt and Palestine till they were conquered by Mu’ezz-li-Dîn-Allah, the fourth of the Fâṭemites of Ḳairwân and the founder of Cairo. Thus in the last year of his reign (969 A. D.) Jerusalem came under the rule of this Egyptian Arab khalîfah, who claimed descent from the prophet’s daughter.