National Institute of Informatics - Digital Silk Road Project
Digital Archive of Toyo Bunko Rare Books

Climate of Central
Nan-shan.

than that of the Western Nan-shan or of the K'un-lun. It indicates
the vicinity of the Pacific drainage area which extends to the adjoining
parts of Kan-su and of the north-eastern uplands of Tibet. Abundant
vegetation clothes the valleys from the westernmost limits of the Pei-ta-ho or Su-chou river's
drainage¹ and makes the big open troughs at the headwaters excellent summer grazing
grounds, notwithstanding their great elevation, above 11,000 feet, and Pāmir-like ap-
pearance. Further to the south-east increasing snow and rainfall permits of plentiful forest
growth in the valleys of the Richthofen Range draining into the Kan-chou river.²

Cultivated area N. of
Nan-shan.

Along the northern foot of this range at an elevation of about 5,000—6,000 feet, stretches
a broad belt of fertile alluvial fans, separated in places by scrub-covered
table-lands.³ Its northern limit is formed by the barren hill-chain
overlooking the middle course of the rivers of Kan-chou and Su-chou,
and belonging to the Ala-shan system of southernmost Mongolia. Over great parts of this
second region, cultivation is assured by abundant irrigation from the rivers and also by the
fact that from about the longitude of Kan-chou city eastwards, climatic conditions along the
fertile foot of the Nan-shan permit of cultivation dependent on snow and rainfall only.
Hence we find in this region not only large and populous oases occupying the alluvial fans
of the Su-chou and Kan-chou rivers, but also an almost continuous chain of smaller village
tracts skirting the foot of the mountains beyond those fans.

Passage through N.W.
marches of Kan-su.

The physical features here briefly indicated have made this region historically a very
important 'land of passage' between China and Central Asia. For the
Chinese its possession was indispensable in economic and military
respects ever since their policy of Central-Asian expansion more than
two thousand years ago first opened the route through the north-western marches of Kan-su
and along the Su-lo-ho into the Tārim basin. But before their advent and during the periods
when their control of the route ceased, the abundant winter grazing which parts of this
region afford, made it also for centuries a goal of conquest for a succession of nomadic
nations.⁴

Cultivated areas on
Etsin-gol.

A region of very different character stretches from the barren hill-range north of the
chain of oases down to the terminal basin of the Etsin-gol. We find
there, indeed, two narrow strips of cultivation, those of Chin-t'a and
Mao-mei, lying beyond the gorges in which the rivers of Su-chou and
Kan-chou, respectively, have cut their way through that range.⁵ But apart from them the
whole of this region consists of desert ground, affording now but limited grazing in the delta
which the Ets-in-gol forms from a point about 60 miles below the lower end of Mao-mei
cultivation.⁶ Amidst the almost waterless valleys and plateaus which adjoin the Etsin-gol
on the east and west, even camel grazing is scanty and confined to rare patches of ground.

Etsin-gol valley as
highway.

Nevertheless, the Etsin-gol valley has always possessed considerable importance as a
highway for nomadic migration and trade from Mongolia into north-
western China. It resembles in this respect the territory of ancient
Lou-lan, now completely abandoned to the desert, and this affinity is
curiously illustrated also by the evidence of desiccation within historical times which the
Etsin-gol delta and its mediæval remains afford.⁷ The fact that the river loses itself in two
separate lake-beds (Sheet No. 44. C. 4) is also of interest with regard to the observations
made above concerning the simultaneous existence in earlier periods of two terminal basins
of the Su-lo-ho, and concerning that of the Lou-lan delta by the side of the Kara-koshun.⁸