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

In the southern marginal belt of the basin, stretching along the foot of the K'un-lun
from Karghalik to the Lop tract, conditions differ in various ways.
Southern belt of oases. Here only one oasis of real importance is found, that of Khotan, and
the rest in most cases are separated from each other by considerable
expanses of true desert. To the east of Niya, over a marching distance of some 350 miles to
Vâsh-shahri, the westernmost hamlet of Lop, there is met now only the single small oasis of
Charchan, and our historical records show even this to have been in abeyance again and again
during intervals of centuries. ⁵

Geographical conditions duly reflected by the map fully account for the thinness, or
else the complete absence, of cultivated areas along the whole belt.
Khotan oasis. With the single significant exception of Khotan, all oases in the plains
are separated from the debouchure of the rivers which supply their
irrigation by great stretches of absolutely sterile gravel forming the glacis of the K'un-lun.
But in the case of the Khotan tract the vast volume of water brought down by the Yurung-
kâsh and Kara-kâsh rivers has led to the formation of large and extremely fertile beds of
alluvial loess almost reaching their debouchure from the mountains. The combined presence
of an extensive area of fertile soil and of abundant water, aided by the configuration of the
ground particularly favourable to its full use for irrigation, adequately accounts for the pre-
sence here of a large, and throughout historical times a very important, oasis. ⁶

Elsewhere along the foot of the K'un-lun the big glacis causes much of the water
brought down by the rivers to be lost on its way from the foot of the
Irrigation by kara-su mountains through evaporation or absorption in its huge gravel de-
and ak-su. posits. Near its northern edge however, some of the water thus
absorbed comes to the surface again in the form of springs. The supply of irrigation furnished
by them, known as kara-su, or 'black water,' is of great importance. Without it cultivation
would be greatly restricted in all oases of this region and in many altogether impossible;
for it is only during the height of the summer, when the snow and ice on the big mountain
ranges melt, that flood water (distinguished as ak-su, 'white water') passes across the broad
gravel glacis in such volume as to provide ample irrigation, and more, for the oases beyond. ⁷

The same subterraneous drainage from the rivers debouching on the gravel glacis
makes it possible for desert vegetation to subsist in the sandy tracts
Subterraneous along the southern edge of the bare dune-covered wastes of the Takla-
drainage. makân or skirting the oases. ⁸ It also accounts for the rare wells which
permit traffic to be maintained through, or along, these areas of desert vegetation east of the
line of existing oases.

Excepting Khotan and Karghalik, all oases of the southern belt are 'terminal oases,'
i.e., they occupy the furthermost ground at which the water supply
Location of southern derived from the rivers of the K'un-lun can be utilized for cultivation.
cases. Their location is primarily determined by the presence of fertile loess
soil, and this itself owes its existence to the moisture brought there, either by the summer
floods or by subsoil drainage; for it is only this moisture and the vegetation it supports which
can retain the fine alluvium washed down from the mountains as well as the sub-aerial de-
posits of fine 'sand' constantly brought by the dust-laden desert winds from the north and
north-east, and then protect the loess thus formed from the powerful erosive action of the
same winds. ⁹

When discussing elsewhere this process constantly at work in the region here described,