NAIN SING'S IIyDROGRAPIIY. 151
To return to Nain Sing's report, he saw a snowy range extending from Tårgot Lhå to the east. There is no sign of such a range in reality. East of Targogangri there is a broad, open valley and east of it comparatively low mountains. But south of Ngangtse-tso and Marchar-tso, Nain Sing's Dartt Cho, there is a range, stretching east and west, which I have called Ngangtse Range, no other name existing. It is impossible to reconcile Nain Sing's ranges with facts. South of the eastern end of Ngangtse-tso he has two ranges at resp. 2 2 and 37 miles' distance. The latter may be meant to be the water-parting, although this is in reality 45 miles south, namely, the great range Pabla which is the western continuation of Nienchen-tang-la. South of the S.E. corner of Dangra-yum-tso Nain Sing has a range at to miles' distance, whereas in reality the principal range is at 55 miles from the same point. From Tårgot Lhå to Gyåkharma peaks the snowy range is given as t So miles long, which must be along all the windings and bends of the range, for else the distance between the two terminal peaks is only a little over 140 miles. These mountains along the western shore of Dangra-yum-tso are the best, but the southern ranges are very uncertain, which is not surprising, for from Nain Sing's route there is no possibility to judge as to their situation.
As the orography is wrong one could not expect much of Nain Sing's hydrography. Nobody had heard of his Dobo Dobd Cho, supposed to be in connection with Kyåring Cho by the river Duba or Pårå Sangpo. All watercourses in this region go with the Tagrak-tsangpo to the west end of Ngangtse-tso, or exactly in the opposite direction. But there is a district Tova-tova south-east of Ngangtse-tso. Trotter may be said to be right in his supposition that Nain Sing's southernmost range is not the watershed of the Brahmaputra, for this is situated further south. When I had crossed the Sela-la I expected to come down to a river flowing east and northeast and piercing the Nien-chen-tang-la to Kyaring-tso. For south of his southernmost range Nain Sing has a rather long river, Dumphu or Hotå Sangpo going to that lake. But in reality all watercourses streamed westward and belonged to the Brahmaputra system. So the Ota-tsangpo, as the river was called, proved to be much shorter. Of the lakes Ngangon Cho and Siro Cho I could get no information and those Tibetans I asked had not heard the names. The twin lakes Mun-tso were known and said to be situated west, not south of Dangra-yum-tso. Every-
is a quite natural and practical boundary», and I had even given the names of all the lakes situated in the depression which I regard as the northern boundary of the system, a view that is strongly corroborated by the geological structure of the whole system. But it is more surprising that he says that Nain Sing had travelled more than 800 miles along the northern side of a range of snow mountains. Such a view could be accepted in 1874 when Walker wrote his general report, for then Nain Sing's journey stood quite alone in these parts of Tibet. But in 1909 even a rather elementary geographical knowledge would be sufficient to understand that there is no snowy range, 800 miles long, south of Nain Sing's route, but that there are innumerable ranges, most of which are bare of eternal snow. Between 1874 and 1909 the whole history of exploration in this interior part of Tibet is included. From the definition I had already given of the physical boundaries of the system, it was easy to see that Nain Sing did not at a single point come in contact with Transhimalaya, before he moved eastwards from Ngangtse-tso into regions which are still known only from his description.
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