The northern boundary of Tibet is formed by the great chain north of the Indus, to which Humboldt, following Chinese geographers, has given the name of Kouenlun. Our knowledge of the appearance and course of this chain of mountains, by which Tibet is separated from Yarkand and Khoten, is so extremely limited that, except as to its general direction, very little can be said regarding it. The only conclusion which can be drawn from the scanty notices of it by travellers is, that it must be of extreme height and covered with perpetual snow. Many of the principal ramifications which it sends down towards the Indus are very elevated, and immense glaciers descend in their valleys, so that, except in a very few places, the main chain cannot be seen from the valley of the Shayuk, the mountains in the immediate vicinity of that river in general obstructing the view.
PASSES ACROSS KOUENLUN.
I am not aware of more than four places in which passes exist across the Kouenlun. The most westerly of these, called in Balti the pass of the Muztagh, lies at the source of the right branch of the Shigar river, a stream which joins the Indus opposite the town of Iskardo. The road over this pass to Yarkand was formerly frequented by merchants, but has for many years been disused, the reason assigned being the danger of plunder by the hordes of robbers beyond. As described to me by persons who had crossed it, the snow is reached after ten days' journey from Iskardo, and continues during three marches. It is said to be quite impracticable for horses, from which it may, I think, be inferred that there are numerous glaciers.
The second pass is that marked in Vigne's map as the Alibransa pass, at the head of a considerable tributary which joins the Shayuk river opposite Khapalu. The enormous glacier over which this road runs, by which, in conjunction with the lateness of the season, Mr. Vigne's attempts to cross the pass were frustrated, has been well described by that traveller[33]. I did not, while in Tibet, meet with any one who had crossed it, and I was assured by the inhabitants of Nubra that they were not acquainted with any road from the upper part of their valley, either towards Khapalu or towards Yarkand.
The third pass, and the only one now frequented, is that of the Karakoram, an extremely easy though very elevated one. The most easterly pass of which I find any notice occurs on the road between Ruduk and Khoten; it is mentioned by Moorcroft[34], but without any account of the nature of the road, or the elevation of the mountains.
To the westward of Karakoram, the direction of the Kouenlun is seemingly as nearly as possible parallel to the Indus, but to the east of that pass nothing certain is known regarding it. In Humboldt's map it is laid down as running nearly from west to east, on the authority of Chinese geographical works. Its course is unquestionably to the north of the Pangong lake, but till it has been explored by European travellers its direction must, I think, be regarded as involved in much doubt. Another lofty range, however, unquestionably runs parallel to the Indus from south-east to north-west. This range, which is continuous with that by which the Indus and Shayuk rivers are separated, terminates (or more properly originates) in the still almost unknown mass of mountains which lies to the north of lake Manasarawar. Between this chain and the Kouenlun is situated a tract of country of unknown extent, which seems to be made up of a number of isolated lake-basins quite unconnected, not only with one another, but with the general drainage of the country by which they are surrounded.
PANGONG LAKE.
If we except the basin of the Pangong lake, into which Moorcroft and Trebeck descended after crossing the range of mountains parallel to the Indus, every part of this country must be viewed as a terra incognita. It cannot, I think, be doubted, from the description of the Pangong lake given by Moorcroft and Trebeck, that the basin in which it rests had originally an outlet at its north-west extremity, discharging itself along the valley of Tanktse into the Shayuk. The country to the eastward is so totally unknown, that it is impossible to conjecture whether the little lake-basins of which it is said to consist, discharge themselves towards the Pangong lake, or southward into the Indus.
BOUNDARIES OF TIBET.