The level region over which the Lop-nor has wandered for thousands of
years from north to south is called the Lop desert. Its stillness is
broken only from time to time by easterly storms which roll like thunder
over the yellow clay ground. In the course of ages these strong spring
storms have ploughed out channels and furrows in the clay, but otherwise
the desert is as level as a frozen sea, the places where Lop-nor
formerly spread out its water being marked only by pink mollusc shells.

On the north the Lop desert is bounded by the easternmost chains of the
Tien-shan, which the Chinese also call the "Dry Mountains." They deserve
the name, for their sides are hardly ever washed by rain; but at their
southern foot a few salt springs are to be found. Round them grow reeds
and tamarisks, and even in other places near the mountains some
vegetation struggles for existence.

This is the country of wild camels. Wild camels live in herds of half a
dozen head. The leader is a dark-brown stallion; the mares are lighter
in colour. Their wool is so soft and fine that it is a pleasure to pass
one's hand over it. Several herds or families are often seen grazing on
the same spot. They look well-fed, and the two humps are firm and full
of fat. In spring and summer they can go without water for eight days,
in winter for two weeks. For innumerable generations they have known
where to find the springs: the mothers take their young ones to them,
and when the youngsters grow up they in their turn show the springs to
their foals. They drink the water, however salt it may be, for they have
no choice, but they do not stay long at the meadows by the springs, for
their instinct tells them that where water is to be found there the
danger is great that their enemies may also come to drink.

Against danger they have no other protection than their sharply
developed senses. They can scent men at a distance of twelve miles. They
know the odour of a camping-ground long after the ashes have been swept
away by the wind, and they avoid the spot. Tame camels passing through
their country excite their suspicion; they do not smell like wild ones.
They are shy and restless and do not remain long at one pasture, even if
no danger threatens.

In some districts they are so numerous that the traveller cannot march
for two minutes without crossing a spoor. Where the tracks all converge
towards a valley between two hills, they probably lead to a spring. On
one