4 BIRD'S-EYE VIEW OF INNERMOST ASIA CH. I
grazing for their flocks, at least at certain regular seasons, deserts in which populations driven out from their seats or harassed by foes can safely seek refuge for a time, are not such as face us in most parts of the huge basin between the Celestial Mountains and the K`un-lun.
By far the greater part of this basin is filled by the dune-covered Taklamakan and the wastes of hard salt crust or wind-eroded clay of the Lop desert which stretch almost unbroken for a total length of over 800 miles from west to east. In them the absence of moisture bans not only human existence but practically also all animal and plant life. Conditions are almost as forbidding in the high mountains and plateaux of the K`un-lun. There vegetation is to be found only at great elevations where the proximity of glaciers provides moisture and allows vegetation to grow for a few months in the year under semi-arctic conditions, or else in the extremely confined space which the streams fed by those glaciers leave at the bottom of deep-cut narrow gorges. It is solely to the water carried down by these streams that the oases scattered along the edges of this and the basins adjoining eastwards owe their existence; for nowhere is cultivation of any kind possible unless irrigation is provided by canals. It is clear that the almost total absence of atmospheric moisture which such conditions imply directly results from the geographical position of the basins. A glance at the map is enough to show how vast are the distances which separate them on all sides from the seas and their life-giving vapours.
Where Nature has been so chary of the gifts which create the resources necessary for human existence and favour close occupation, it is obvious that the ground, however
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