Sec. i] THE OASIS OF KUA-CHOU AND ITS HISTORICAL IMPORTANCE 1093
which by their position along the north. foot of the Nan-shan and' on the line of the great route leading westwards facilitated Chinese commercial and political expansion into the Tarim Basin." Without the provisions, etc., thus available locally as far as Tun-huang, the Chinese missions, caravans, and military expeditions would have found it still more difficult than it was to prepare for, and safely overcome, the formidable obstacles presented to their progress by the sand and salt wastes of the Lop Desert. Kua-chou was, no doubt, a valuable link in this chain of oases which lay behind, and were sheltered by, the Emperor Wu-ti's extension of the Great Wall.. But its local importance is likely to have considerably increased when the Chinese occupation of Hami in A. D. 73 opened up a new route towards the Western Regions.'
This route, though longer than that through Lou-lan or `the new northern Route ', crossing as yet unexplored wastes of the westernmost Pei-shan, avoided the worst of their physical difficulties, want of water, and has for this reason, no doubt, remained to the present day by far the most frequented and important of all routes connecting Chinese Turkestan with Kan-su.1e It is by following this route which connects An-hsi with Hami that the distance to be covered across desert ground bare of local resources is most reduced and an oasis of considerable size reached soonest. Hami is admirably adapted by nature to form a bridge-head, as it were, for the safe crossing of the Pei-shan, and a glance at the general map shows that by starting for it direct from An-hsi instead of via Tun-huang traffic coming from the side of China most effect a considerable saving in distance. This explains the continued use down to our day of the An-hsi—Hami route as the main line of communication across the ` Gobi separating China and Central Asia, and also the special importance which old Kua-chou must have claimed as its starting-point, notwithstanding the local limitations. Nor should another consideration be forgotten. This An-hsi—Hami route finds its direct continuation southwards in a well-known and much-frequented route, which leads across the Nan-shan ranges by easy passes to the plateaus of Tsaidam, and thence over the Tibetan highlands straight to Lhassa." Thus An-hsi lies on the most direct line of communication connecting Mongolia with Tibet, and may on this account, like Tun-huang in earlier times, lay claim to be one of the great cross-roads of Asia.
SECTION II. —OLD REMAINS NEAR AN-HSI AND HSÜAN-TSANG'S YO-MEN KUAN
In view of the importance thus attaching to the tract of old Kua-chou, I feel doubly glad that my enforced stay at An-hsi allowed time for interesting archaeological obwrvations in the neighbour. hood. My previous explorations had enabled me to trace the line of the ancient Chinese Limes to within about 35 miles west of An-hsi,' and left practically no doubt that it must have continued past it eastwards. Local information gave no clue to any remains of it. Some large towers, which on the march from Kua-chou-k`ou we had sighted far away to the west, were reported by Surveyor Ram Singh, whom I sent on a reconnaissance tour in that direction, to be of recent origin.2 But on his way to the western edge of An-hsi cultivation he had come across two ruined towers on waste
" See above, pp. 723 sq.
is Cf. Chavannes, Les pays d'occident, T`oung pao, 2907, p. 20; also above, p. 732.
16 For the route from An-hsi to Hami, cf. below, pp. 1141 sq.
" This route to Lhassa is regularly followed by pilgrims from Mongolia. It leads up the valley of the Ta-shih River past Shih-pao-ch`êng to the Kashkar Pass, as described in Desert Ca/hay, ii. pp. 256 sqq. (see Map No.82), and thence to
Tsaidam. It was by this most direct route that in 1904 the Dalai-lama on his flight from Lhassa made his way to Mongolia.
Cf. above, pp. 605 sq.; Map No. 8r. B. 3.
2 The Surveyor's report was correct as regards the tower of Lei-tun-Izû (Map No. 81. c. 2), which he actually visited. But, when exploring this ground in 1914 from the west, I succeeded in tracing the line of the Limes wall with its here badly decayed towers to within a couple of miles of it.