sometimes asserting that it was only by fraud that the prophet Muhammad interposed and acted as spokesman for the divine Imam 'Ali. Of this type is the Shi'a which forms the state religion of modern Persia, spreading westwards into Mesopotamia and eastwards into India. The commonest belief, prevalent in the modern Shi'a, is that there were twelve Imams of whom 'Ali was the first, and Muhammad al-Muntazar, who succeeded at the death of his father the eleventh Imam al-Hasan al-Askari in 260 A.H. (=A.D. 873) was the last. Soon after his accession Muhammad Al-Muntazar "vanished" at Samárrá, the town which served as the 'Abbasid capital from A.H. 222 to 279. The mosque at Samárrá is said to cover an underground vault into which he disappeared and from which he will emerge again to resume his office when the propitious time has arrived, and the place whence he is to issue forth is one of the sacred spots visited by Shi'ite pilgrims. Meanwhile the Shahs and princes are ruling the faithful only as deputies of the concealed Imam. The disappearance of Muhammad al-Muntazar took place more than a century after the fall of the 'Umayyads but we have anticipated in order to show the general tendency of the Shi'ite ideas which were prevalent even in 'Umayyad times, especially in Northern Persia, and did much to promote the revolt against the secularised 'Umayyad rule.
A curious importance also is attached to the date. The disaffection of the mawali came to a head towards
