r 128 THE NORTH-WEST FRONTIER OF KAN-SU [Chap. XXVII
Richthofen, To-lai-shan, Alexander III, and Suess Ranges, and in which gather the head-waters of the rivers of Su-chou and Kan-chou as well as of the Su-lo Ho. From an elevation of about 11,000 feet upwards all these valleys are remarkably . easy, forming big basins which are almost flat at their bottom and rise with grassy down-like swellings towards the foot of the flanking ranges.9
Between that elevation and a height of about 13,000 feet above sea-level they afford excellent summer grazing, far richer than any I had seen since Kashmir. The extent of this may be
estimated from the fact that the open upper portion of the valley of the Pei-ta Ho (Map No. 89) is not less than 70 miles long in a straight line, with a width up to 12 miles or more, while the length of the upper Kan-chou River valley corresponding in character is still greater.
It is, of course, the distinctly moister climate which accounts for the abundance of alpine grazing to be found in these high valleys. The contrast with the bleakness prevailing on
corresponding ground in the mountains south of An-hsi and Tun-huang is striking. Enough of
this life-giving moisture passes over the snowy crest-line of the Richthofen Range to clothe its north-eastern slopes also with abundant vegetation. Where these jut out in broad spurs, as from
the Ma-yang Ho eastwards to Kan-chou and beyond, our explorations of 1907 and 1914 have shown not merely fine grazing valleys, but also extensive forest growth. The economic importance of this climatic change is well brought out by the fact already emphasized elsewhere that in the submontane tract south of Kan-chou we soon reach the dividing line beyond which cultivation becomes practicable without irrigation and dependent wholly on rainfall.10
Favourable physical conditions such as these were bound to make the utter neglect of the splendid grazing grounds afforded by those big Nan-shan valleys all the more striking. Mountain tracts, which could maintain tens of thousands of cattle and horses during the summer months and,
to a sufficiently hardy race, would afford attractions for nomadic existence quite equal to those of the Alai or of the famous grazing valleys in the Central and Western Tien-shan, were found
absolutely uninhabited during the warmest season of the year. During three weeks of strenuous travel, covering a total marching distance of some 32o miles over such extensive areas as the map shows, we did not meet with a single human being, apart from a few adventurous Tungans working gold pits at an elevation close on 14,000 feet near the watershed between the Hung-shui-pa and Kan-chou river sources.
Racial and political facts combine to explain this neglect. The deep-rooted traditional aversion of the Chinese, where undiluted by other elements; to the life of herdsmen and such
nomadic or semi-nomadic existence as it implies is well known. -It has always been a factor of
fundamental importance for the civilization and history of Eastern Asia. It must necessarily prevent its peoples from exploiting for their own benefit the cattle-raising facilities offered by these
Nan-shan valleys. On the other hand, it is equally obvious that, taught by the sad experience of long centuries to apprehend constant danger of aggression from their neighbours in the great plains northward, whether Huns, Turks, or Mongols, and from Tibetan tribes on the south also, the
Chinese cannot possibly care for the presence of similar troublesome nomads on the mountain flank of these far-advanced Kan-su marches, the key to Chinese power in Central Asia. It is clear that
it must at all times have been a direct interest of Chinese border policy to keep nomads, whatever their race, out of this mountain region. Nor is there reason to doubt that, whenever political conditions permitted, this safeguard was applied with the same ruthless thoroughness which was exhibited in clearing these mountains of all Tungans after the last rebellion.
It appeared, therefore, a strange contradiction to this time-honoured policy when, on my
9 For photographs illustrating the scenery in these valleys, t0 Cf. Third Journey of Exploration, Geogr. journal, 1916,
see Desert Cathay, ii. Figs. 236, 238, 241-6. xlviii. p. 199.