scended into the Tarim basin and after
defeating the Chinese in 670 held the Four Garrisons till 692, when
the fortunes of war were reversed. But the field was not left clear
for China: the power of the northern Turks revived, and Mohammedanism,
then a new force but destined to ultimate triumph in politics and
religion alike, appeared in the west. The conquests of the Mohammedan
general Qutayba (705-715) extended to Ferghana and he attacked
Kashgar. In the long reign of Hsuan Tsung China waged a double warfare
against the Arabs and Tibetans. For about thirty years (719-751) the
struggle was successful. Even Tabaristan is said to have acknowledged
China's suzerainty. Her troops crossed the Hindu Kush and reached
Gilgit. But in 751 they sustained a crushing defeat near Tashkent. The
disaster was aggravated by the internal troubles of the Empire and it
was long before Chinese authority recovered from the blow.[487] The
Tibetans reaped the advantage. Except in Turfan, they were the
dominant power of the Tarim basin for a century, they took tribute
from China and when it was refused sacked the capital, Chang-an (763).
It would appear however that for a time Chinese garrisons held out in
Central Asia and Chinese officials exercised some authority, though
they obtained no support from the Empire.[488] But although even late
in the tenth century Khotan sent embassies to the Imperial Court,
China gradually ceased to be a Central Asian power. She made a
treaty with the Tibetans (783) and an alliance with the Uigurs, who
now came to the front and occupied Turfan, where there was a
flourishing Uigur kingdom with Manichaeism as the state religion from
about 750 to 843. In that year the Kirghiz sacked Turfan and it is
interesting to note that the Chinese who had hitherto tolerated
Manichaeism as the religion of their allies, at once began to issue
restrictive edicts against it. But except in Turfan it does not appear
that the power of the Uigurs was weakened.[489] In 860-817 they broke
up Tibetan rule in the Tarim basin and formed a new kingdom of their
own which apparently included Kashgar, Urumtsi and Kucha but not
Khotan. The prince of Kashgar embraced Islam about 945, but the
conversion of Khotan and Turfan was later. With this conversion the
connection of the Tarim basin with the history of Buddhism naturally
ceases, for it does not appear that the triumphal progress of Lamaism
under Khubilai Khan affected these regions.

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