Page:Encyclopædia Britannica, Ninth Edition, v. 23.djvu/361

GEOGRAPHY.] have maintained, in accordance with information from natives of Tibet and Assam, that it enters the Assam valley and is the principal source of the Brahmaputra river, of which the Lohit Brahmaputra river is the eastern source; the latter have maintained, on the authority of Chinese geographers, that it flows into Burma and is the principal source of the Irawadi river. But now its eastern basin has been explored, and the Lohit Brahmaputra has been found to have its sources in a range bordering the Giama-Nu-chu; the Yaro-tsanpo must therefore necessarily pass into Assam, and measurements of the discharges of the principal rivers entering Assam from the north conclusively identify it with the Dihong. That river, which receives the Lohit Brahmaputra a little below Sadiya (450 feet above the sea), has been explored upwards into the Himalayas to a point within 100 miles of Gya-la-Sindong; but as yet nothing is known of the connecting channel, except that it must have a fall of about 7000 feet, or as much as the entire fall of the Yaro-tsanpo in its upper course of 900 miles.

The Tibetan basins to the south of the Yaro-tsanpo which are included between the Himalayan chains of water-parting and of high snow-peaks are the Bheri, the Kali Gandak, and the Buria Gandak, subject to Nepal; then the following, which are subject to Lhása:—(1) the Tirsuli Gandak, on the direct road from Kathmandu to Dokthol via Kirong (9700 feet); (2) the Bhotia Kosi, through which the road from Kathmandu to Shigatze passes via Nilam Jong or Kuti (13,900 feet) into (3) the Arun-Barun basin, 120 miles by 30, which embraces the Dingri Maidan and Shikar Jong plateaus and the great Chomto Dong Lake (14,700 feet); this same road, after passing Sikkim and western Bhutan, where the chain of high snow-peaks, including Kanchinjinga (27,815 feet), is the water-parting, traverses (4) the Lhobra, (5) the Cha-yul, and (6) the Mon-yul basins, which are also crossed by the road between Chetang and Tawang. East of the 93d meridian the height of the peaks of the outer Himalayan chain falls to about 15,000 feet; the inner line of water-parting recedes northwards, and with it the boundary of Lhása rule. The included basins are occupied by independent semi-savage tribes,—Miris, Abors, Mishmis, &c.; but about the 97th meridian Lhása rule again asserts itself. The mountains again rise to a great height in the Nechin-Gangra range, the eastern most Himalaya, which terminates about the 98th meridian in spurs thrown off to the north and south, parting the waters of the Lohit Brahmaputra and the Giama-Nu-chu. The southern spur bends westwards in horse-shoe fashion round the Zayul basin, and then merges into the range which separates upper Assam and eastern Bengal from Burma. Lhása rule extends over Zayul, and for a short distance down the valley of the Giama-Nu-chu, embracing some tracts which lie outside the geographical limits of Tibet, as lower Zayul, where the elevation falls below 4000 feet and the climate is so warm that criminals are sent there from Lhása as a punishment.

The Giama-Nu-chu is called by the Chinese the Lu-kiang or Lu-tse-kiang. Its course is known down to about 27° 30′ N. lat., a few marches below Bonga, on the left bank, where the Abbé Desgodins established a mission station temporarily; but nothing certain is known of its lower course. It is generally believed to be identical with the Salwin river, which the Chinese also call the Lu-kiang; but the similarity of name is not conclusive of identity, for the Lu country covers a large area, and its name may be given to a second river rising among the Ly-su and Lu-tse tribes to the south. Nothing certain is known of the Salwin above 25° N. lat.; where it is crossed on the road from Tali-fu to Bamo, it is almost certainly of too small a volume to have its sources farther off than, say, 250 miles in the southern Tibetan scarp, and not far away in the heart of Tibet. There is a considerable probability that the Giama-Nuchu is the source of the Irawadi, and thus that Chinese geographers have been right in assigning a Tibetan origin to that river, though wrong in identifying it with the Yaro-tsanpo.

The Dayul plateau, with the lofty mountains of Kokarpo to the north near Dayul (11450 feet) and Dokela to the south near Bonga, lies between the Giama Nu-chu and the Chiamdo or Lan-tsan-kiang; the latter river is believed to become the Mekong of Cambodia. The Ou-kio river of the Abb6 Desgodins rises in an important valley between the Giama-Nu and Chiamdo rivers and, flowing past Dayul, joins the former above Bonga. Next comes the Makham plateau, between the Chiamdo and the Di-chu, of which the chief town (11,900 feet) is called Gartok by Tibetans and Kiangka by Chinese. East of the Di-chu or Kin-shakiang lie the plateaus of Batang, Litang, and Darchendo, which, though geographically and ethnologically Tibetan, are directly under China. The last two are separated by the Ja-chu, which is known as the Yalung in its southerly course to join the Kin-sha; the united streams flow east wards through China as the Yang-tse-kiang or Blue river.

The western Hor country lies to the north, on the direct Western route between Ladak and Lhasa; it is a region of extensive Hor grassy plains and numerous lakes, some of great size, and countr y occasional hill ranges, which, though often snow-covered, are of no great elevation above the tableland. It is in habited by nomads—Cháng-pas of local origin and Khampas from the east—and occasional communities of golddiggers and of traders in salt and borax, which are plentifully found on the margins of the lakes. Thok Daurakpa (15,300 feet), the centre of a large gold-field, is the chief settlement. Within a remarkable basin, surrounded by high hills and enclosing the great Dangra-Yum Lake and a cluster of small but well-built villages, Ombo, are lands which produce a profusion of barley at an altitude of 15,200 feet, a unique instance of cultivation at so great a height, no other cultivation occurring within 300 miles on either side. The Tengri-nur or Nam-cho, 150 miles in circumference and 15,350 feet above the sea, lies to the north-west of Lhása; and beyond it there is said to be a still larger lake, the Chargut-cho, and numerous smaller lakes, to one or more of which the sources of the Giama-Nu-chu may perhaps be traced, though as a rule the lakes in this region have no outlet. The Ninchen-thangla range lies between the Tengri-nur and Lhása; it is considered by some writers to rival the Himalayas, but is probably not more than 300 miles long nor anywhere higher than 24,000 feet above the sea.

The Cháng-táng attains its greatest width (over 500 miles) on the meridian of 85°; north of Lhása it contracts to 400 miles, and is probably narrowest (140 miles) on the meridian of 97°. It is covered to a very considerable extent, probably everywhere below 16,000 feet, with a succulent grass, which forms from May to August the softest of green carpets and furnishes an abundance of green pasture. Willow and tamarisk are occasionally met with on the margins of the lakes; but as a rule there is little wood or scrub of any kind, and cultivation only in very exceptional localities, such as Ombo. Myriads of wild animals—chiefly the yak and the antelope, but also the ass and the camel—roam over the entire region, but mostly congregate in the uninhabited northern portion; their argols furnish a plentiful supply of fuel, without which it would be impossible for travellers to cross the country, as there are stretches of hundreds of miles in which no other fuel is procurable. As the Cháng-táng narrows to the east, its surface becomes corrugated with chains of low hills. Here too there is more marsh land than on the west: the Odontala plateau at the sources of the Hoang-ho river is described by Prejevalsky as one vast bog in summer, during the prevalence of the south-west monsoon from the Indian Ocean. The openings between the meridional hill ranges to the south permit the rain clouds to pass up to much higher latitudes before discharging their moisture than on the west, where they are faced by the great longitudinal ranges of the Himalayas.

The Kuen-Lun has been identified, geologically, by Stoliczka, as far west as the Victoria Lake on the great Pamir, in 74°E. long.; it has been surveyed between 77° and 82°, where it rises to more than 22,000 feet, and