The description in Chi Chao Nan’s Hydrography is distinguished by the same careful conformity with the truth and conscientiousness as all other Chinese geographical descriptions. Compare the description of Kailas (Kang-rinpoche) with what I have already said about it.
Lang-chuan-ka-pa-pu is the Chinese translation of the Tibetan Langchen-kabab, which literally means the “Source of the Sutlej.” When the Chinese author informs us that east of Langchen-kabab lies Tamchok-kabab, which is the source of the river Yere-tsangpo (Brahmaputra), we must admit that his description is quite in accordance with the truth, as I, the first European to visit this country, have myself discovered; for on the Tamlung-la I stood on the pass which parts the water between the Brahmaputra and Sutlej, and immediately to the south of the pass I saw Gang-lung-gangri and the glacier from which the Tage-tsangpo takes its rise, and in which the source of the Sutlej lies.
It is further said that the lake Gunchu-tso has two source streams—one from the north-east, from the mountain Ta-ko-la-kung-ma, which is evidently identical with D’Anville’s Tacra-concla; the other from the west side of the pass Marium-la: an account which agrees with Ryder’s map in all particulars. At present the Gunchu-tso is completely cut off and is salt; it therefore is no longer connected with the Sutlej system. But 147 years ago it had an outlet which ran partly underground, and then, rising up again, joined the Langchen-kamba or Tage-tsangpo. And that the Tage-tsangpo was at one time considered by the Tibetans to be the headwater of the Sutlej is apparent from the fact that its name, Langchen-kamba, is still applied to the upper of the two sacred source streams in the valley of the Tage-tsangpo.
And, again, it is said: This water, that is, the water of the Langchen-kabab, or the headwater of the Sutlej, forms the lake Ma-piu-mu-ta-lai, the Tso-mavang or Tso-mavam, as the name is also pronounced; on D’Anville’s map (Map 2) it is written Ma-pama Talai, and D’Anville explains that Talai signifies lake. He might have added that it is the same word as in Dalai Lama, the priest, whose wisdom is as unfathomable as the ocean; for the Chinese word Talai or Dalai means ocean. By the use of this word the Chinese author wished to imply that Tso-mavang is much larger than the other lakes mentioned in his text.
The surplus water, as there is every reason to assume, flowed in the year 1762 from Tso-mavang through the channel to Langak-tso. The length of the channel was 60 li, which corresponds to my 5½ miles. All the northern tributaries which flow into the two lakes from the valleys of the Trans-Himalaya are correctly noted. The lake Langak is called Lang-ka. On D’Anville’s map, the material for which was supplied by the Jesuits who lived in Pekin in the time of the Emperor Kang Hi (at the beginning of the eighteenth century), the lake is named Lanken. On the same map the river flowing thence westwards is called Lanc-tchou (Sutlej), but it is suggested, absurdly enough, that it is the upper course of the Ganges. D’Anville names the mountains south of Tso-mavang Lantchia-Kepou, which is Langchen-kabab, and the mountains lying to the south-east of them Tam-tchou, that is, Tamchok, in which he quite correctly places the origin of the Yarou Tsanpou, the Brahmaputra. The material for the map of the whole Chinese Empire, which the Jesuits presented to the Emperor Kang Hi in the year 1718, was collected between the years 1708 and 1716, and the Emperor procured information about Tibet through natives, who were prepared for their work by the Jesuits, just as in later times English topographers have trained Indian pundits.
From D’Anville’s map we learn that 200 years ago the Sutlej flowed out of Langak-tso through the bed I have already described. Professor Ogawa’s translation of the Chinese text shows us that even in the year 1762, or perhaps some years before, the river still emerged from the Langak-tso. And it is expressly said that the river Chu-ka-la-ho (Chu-kar, which, however, is said to descend from the north-east instead of the south-east) is only a tributary.
In the year 1846 Henry Strachey found no visible outlet, but he says that there is one underground, and considers it probable that the channel also may carry water when the lake has risen after heavy rains.
On July 30, 1908, I heard from the chief lama of the monastery Dölchu-gompa, who was born in the neighbourhood and was then fifty-five years old, that when he was quite young, water occasionally flowed out of the lake. But when he was ten years old, that would be in the year 1863, this water had failed, and since then no more had been seen. On the other hand, the springs in the bed are constant both in winter and in summer, and are independent of the precipitation. The monks believe that the water comes from Langak-tso, but nevertheless they call it the Langchen-kabab, the river which flows out of the mouth of the elephant.
My investigations on the spot, as well as the Chinese quotation, prove that Colonel S. G. Burrard is quite right in his masterly description of the rivers of the Himalayas and Tibet (Calcutta, 1907), when he includes Tso-mavang and Langak-tso and all their affluents in the drainage basin of the Sutlej, and therefore I will here cite two sentences of Colonel Burrard:
The connection between the two lakes may be taken as established, but that between the western lake and the Sutlej basin is still open to question. If the water from Rakas-tal flows into the Sutlej once a century, and then only for such a short period as to be observed by no one, we shall still be justified in including the lakes in the catchment area of the river.