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Digital Archive of Toyo Bunko Rare Books

the importance of the territory already in ancient times is amply attested by archæological
remains and historical records alike. If we compare this fact with the great extent of that
portion of the cultivated area which now, as the map shows, depends solely on Kārēz irrigation,
the progress made by desiccation in this region receives striking illustration.


Section V.—THE SU-LO-HO BASIN

East of the Lop depression our surveys extended to a series of drainageless regions
which, if not comparable in size to the Tārim basin, yet resemble it
Extent of Su-lo-ho
basin. closely in various physical features of importance and are linked up
with it also in historical interest. Proceeding from the extreme eastern
end of the Lop depression across a dry lake-bed once apparently draining into it, ¹ we enter
directly the lowest portion of the basin of the Su-lo-ho, containing this river's delta and
terminal marshes. ² This basin, as shown on Sheets Nos. 35, 38, 40, extends for some 220
miles from east to west with an average width of 30-40 miles between the foot hills of the
ranges which bound it. These are the western Nan-shan in the south and the utterly barren
Pei-shan northward.

The Su-lo-ho, a considerable river, fed by glaciers and eternal snows of the
Central Nan-shan, descends into the basin at its eastern end. After
Course of Su-lo-ho. breaking through a succession of ranges in gorges, of which those to
the south are as yet unexplored, ³ it skirts a low divide separating its
basin from one much smaller adjoining eastwards. Below the oasis of Yü-mên-hsien the
Su-lo-ho turns sharply westwards. Maintaining this course it passes through the Khara-nôr
lake, supposed to be its terminal basin until our surveys proved this to be situated some 80
miles further west in the salt marshes already referred to. ⁴ On its whole course through the
basin the Su-lo-ho receives only one affluent, the Tang-ho or Tun-huang river, rising on high
plateaus towards Tsaidam. This provides ample irrigation for the large oasis of Tun-huang,
or Sha-chou, which occupies its alluvial fan.

Tun-huang is the only settlement of considerable size in the whole region, and its local
resources were of special value in ancient times when the great natural
Importance of Tun
huang oasis. passage of the Su-lo-ho basin served as the earliest high road of Chinese
expansion into Central Asia. ⁵ It was for the protection of this import-
ant trade-route leading through Lou-lan to the oases of the Tārim basin that the far-flung
westernmost portion of the ancient Chinese border line was constructed towards the second
century B. C. ⁶ The extreme aridity of the desert ground, over which it led past the Su-lo-ho
and its riverine marshes, explains the abundance and remarkable preservation of the ancient
records, etc., brought to light by my explorations along this ruined Limes.

Excepting the narrow belt of desert vegetation which accompanies the river's lower
course and the limited ground capable of irrigation beside the oasis of
Desert features of
basin. Tun-huang, the Su-lo-ho basin consists mainly of slopes of absolutely
bare gravel, corresponding to the 'Sai' of the K'un-lun. Immediately
south of Tun-huang, however, and again beyond the small oasis of Nan-hu in the south-west,
huge accumulations of drift-sand approach or overlie the foot-hills of the Nan-shan. ⁷ These
have been heaped up by the violent east and north-east winds which for a great part of the
year blow down into the basin from the plateaus of Pei-shan,—another case of 'aspiration'.