国立情報学研究所 - ディジタル・シルクロード・プロジェクト
『東洋文庫所蔵』貴重書デジタルアーカイブ

Kua-chou, north-westwards to the foot of the easternmost T'ien-shan, and gains it at the ancient Road
oasis of Hāmi, or Kumul. This route, too, as we have already had occasion to note, is of early through
date, its passage through Hāmi being definitely mentioned in the Later Han Annals.⁸ Through An-hsi
changes largely physical, which we had to consider repeatedly in connexion with Lou-lan, this route to Hāmi.
became in T'ang times the main artery of traffic between China and Central Asia, and remains so
to the present day. I shall have to discuss it and its possible variants on the east and west in
a subsequent chapter.⁸ᵃ Here it may suffice to point out that it is solely on account of its position
where the present highway leaves the Su-lo Ho, to strike across the desert ranges of the Pei-shan
to Hāmi, that the collection of modest villages now grouped as the 'district' of An-hsi figures
more prominently in our maps and in Chinese administrative classification than the far greater and
richer oasis of Tun-huang.

It was different in Han times, when Tun-huang was famous among the four 'commands' of Importance
Ho-hsi, or Western Kan-su, side by side with Liang-chou, Kan-chou, and Su-chou.⁹ Tun-huang of Tun-
derived its importance for the Chinese then from the great advantages which its geographical huang.
position and resources offered, and which are easy to recognize even now when the line of the great
Central-Asian route has finally shifted northward. It represents the largest area capable of con-
tinuous cultivation which can be found now, or is likely to have existed in historical times, between
Su-chou and Khotan, a distance of over 1,200 miles. Compared with its extent of arable land, even
now a compact stretch over twenty miles long from south to north and about sixteen miles at its
widest part, the oases that lie eastward to Su-chou are small, and those in the Lop region insigni-
ficant. It is easy to realize how great in consequence was the value which Tun-huang possessed
for the Chinese at the time of their first advance into the Tārim Basin, and while the most direct
route via Lou-lan remained open. It was increased by the fact that this important base of supplies
for the movements of troops and trading caravans lay so far west, at the very point where the
Lou-lan route entered the great wastes of desert ground wholly devoid of human sustenance.

Tun-huang owes its comparatively large area of cultivation wholly to the fact that it occupies Physical
an extensive and easily irrigated alluvial fan at the very debouchure of a considerable river which conditions
affords an abundant and, at the critical seasons, reliable supply of water. As I have had occasion at Tun-
to emphasize elsewhere, there exists a very close affinity between practically all the physical huang.
features of the lower Su-lo Ho Basin and those of the Tārim Basin. Both are inland drainage
areas of exactly analogous climatic conditions, and probably, as mentioned above, at an earlier
period had their lowest depressions linked up.¹⁰ It is a necessary result of this close agreement in
essential geographical factors that here, as in the Tārim Basin, the extent of cultivation is entirely
dependent upon the natural facilities for irrigation.

At Tun-huang these conditions are more favourable than anywhere else between Su-chou in Irrigation
the east and Khotan or Kuchā in the west. The Tang Ho, or river of Tun-huang, is a river facilities of
of considerable volume, which breaks through the main range of the western Nan-shan and, as Tun-huang.
Captain Roborovsky's fine map on the scale of 1 : 840,000 shows, drains a high mountain area to
the south quite as large as, if not larger than, that drained by the Su-lo Ho. Among the ranges
feeding it there are several which raise their crests well above the permanent snow line, and
must carry extensive snow beds and even glaciers of some size. This is certainly true of the
range which we surveyed on its northern slope between Shih-pao-ch'êng and Ch'ang-ma, and which,
as Map No. 84 shows, has peaks over 20,000 feet high. Its drainage to the south flows mainly