In 692, the Chinese retook their Four Garrisons (Karashahr, Kucha, Kashgar, Khotan) of Central Asia. " During the reign T'cheng yuen, 785-804 a.d., the black- coated Ta shi began a war with T'u fan (Tibet), and the Tibetans were obliged every year to send an army against the Ta shi. On this account the Chinese frontier enjoyed more peace ^." The two most ancient historical edicts of Tibet have been found by Dr. L . A . Waddell upon a lofty pillar of victory which stands at the foot of Potala Hill, under the castles of the ancient kings, now incorporated in the palace of the Dalai lama ; they date between A.D . 730 and 763, are the earliest documents hitherto discovered, and throw a side-light on the ancient history and geography of China. The eighth century is the culminating point of Tibetan power, which was destroyed when the Uighiirs became the masters of the whole country between Pei t'ing and Aqsu. The Uighiirs were of Turkish race ; their ancestor was a descendant of the Hiong nu ; at the time of the Posterior Wei, they were called T'iele (Tolos) and were subject to the Tu Kiue ; they lived on the banks of the Selenga ; in the middle of the seventh century their chief P'u sa rebelled against the northern Tu Kiue, defeated their chief Hie-li qagan, and in 646 they sent an embassy to China. Under T'ai Tsung, the Uighiir tribe became the Han hai Prefecture, and the chief T'u mi tu was appointed commander of the region. Their power went on increasing from the beginning of the eighth century ; at first they were called by the Chinese Hwei ho and later Hwei hu and Wei wu eul ; the Tibetans appear to have named them Dru gu. The expansion of the religion of Mo-ni (Mani), Mani- chaeism, is intimately connected with the history of the ^ From the History of the T'ang (Bretschneider, Arabs, p. 10).
