Islam • 123Hidden Imam. The Shii ulama had never agreed to close "the
gates of ijtihad" like the Sunnis. Indeed, they called a leading
jurist a mujtahid, one who had earned the right to exercise "in-
dependent reasoning" when formulating Islamic legislation.
The Usulis taught that even the shah should obey the fatwah
of the mujtahid whom he had chosen for his mentor, since he
needed his legal expertise. During the seventeenth century
the Usulis did not win widespread support, but by the end of
the century, when it was clear that the Safavid Empire was in
decline, their position became popular. It had become crucial
to establish a strong legal authority that could compensate for
the weakness of the state.
By this time, the empire had succumbed to the fate of any
agrarian economy, and could no longer keep pace with its re-
sponsibilities. Trade had deteriorated, there was economic
insecurity and the later shahs were incompetent. When
Afghan tribes attacked Isfahan in 1722, the city surrendered
ignominiously. One of the Safavid princes escaped the mas-
sacre, and with the help of the brilliant but ruthless comman-
der Nadir Khan, managed to drive out the invaders. For over
twenty years Nadir Khan, who got rid of his Safavid col-
league and made himself shah, pulled Iran together and
achieved notable military victories. But he was a cruel, brutal
man and was assassinated in 1748. During this period, two
crucial developments gave the ulama of Iran a power unparal-
leled anywhere else in the Muslim world. First, when Nadir
Khan had tried, unsuccessfully, to re-establish Sunni Islam in
Iran, the leading ulama had left the empire and taken up resi-
dence in the holy Shii cities of Najaf and Kerbala (dedicated
respectively to Ali and Husain). This seemed a disaster at
first, but in Najaf and Kerbala, which were in Ottoman Iraq,
they had a base from which they could instruct the people
which was out of reach of the temporal rulers of Iran. Second,
during the dark interregnum that followed Nadir Khan's