In 991 Aleppo was added to the Fatimid Empire which, beginning at the river Orontes and the desert of Syria, extended to Morocco. In view of this great success and its danger to the Abbasids the world was informed now from Bagdad that the Fatimid dynasty was spurious; that the first Kalif installed at Mahdiya was no descendant of the Prophet, he was merely the son of that Ahmed who was a son of Abdallah, son of Maimun Kaddah, son of Daisan the Dualist, his mother being a Jewess. Hence he was son of that Ahmed whose emissary, Hussein of Ahwas, had raised up and trained the detestable Karmath, whose crimes, and the crimes of whose followers, had tortured all Islam for a century. That society, or order, which met at the famed House of Science in Cairo, was dreaming of power night and day and struggling always to win it. Power it could reach by supplanting the Abbasids, but not in another way, hence this order aimed at the overthrow of the Abbasids. It also spread secret doctrines by its Dayis (political and religious missionaries) continually. Through this activity the Fatimids were rising. Meanwhile the Abbasids were failing till Emir Bessassiri, a partisan of the Fatimids, seized and held for one year the two highest marks of dominion in Islam, the mint and the pulpit at Bagdad in the name of Mostansir the Kalif at Cairo, and would have held them much longer had not his career been cut short in 1058 by Togrul the first Seljuk Sultan, who hastened to the rescue of the Abbasids. Meanwhile the Dayis from Cairo and their aids filled a great part of Asia with their labors. One of these Dayis, Hassan Ben Sabah, founded a sect, the Eastern Ismailites, renowned later as the Assassins. This Hassan was son of Ali, a Shiite of the old city Rayi, who claimed that his father, Sabah Homairi, had gone from Kufa to Kum and later to Rayi. People from Tus in Khorassan, and others insisted that his ancestors had passed all their lives in Khorassan. Ali, suspected of heresy, made lying oaths and confessions to clear himself; since his success was but partial he strove to increase it by sending Hassan, his son, to the Nishapur school of Movaffik, a sage of eighty years at that period, and the first scholar among Sunnite believers. This sage, it was said, brought happiness and good fortune to all whom he instructed. His school was frequented by multitudes, and the success of his pupils was proverbial. Among his last students were three classmates, later on very famous: Omar Khayyam, the astronomer and poet; Nizam ul Mulk, the first statesman of the period, and Hassan Ben Sabah, who founded a sect upon sophisms, and a State upon murder.