Tibet or Thibet

TIBET or THIBET, a country of Central Asia. It is the highest country in the world, comprising table-lands, averaging about i6,000ft. above the sea, the valleys being at 12,000 to 17,400f t., the peaks at 20,000 to 24,600ft., and the passes at 16,000 to 19,00o feet. It is bounded on the north by Sinkiang, on the north-east by Kuku-nor (Koko-nor, q.v.), on the east by Chwanben (or Chamben or Chwampien or Kham), on the west by Kashmir and Ladakh, and on the south by India, Nepal and Bhutan. The indefinite position of Chwanben (Chwampien) and Kuku-nor, and the doubtful limits between Tibet and Sin kiang prevent any calculation of the area of Tibet ; its popula tion is probably less than 3,000,000.

Origin of Name.

The Tibetans call their country Bod, which word in colloquial pronunciation is aspirated into Bhod or Bhot, and in the modern Lhasa dialect is curtailed into Bla 5. Hence the country is known to Indians as Bhot, and the inhabitants as Bhot-ias. This territory came to be known to Europeans as "Tibet," evidently because the great plateau, with its uplands bordering the frontiers of China, Mongolia and Kashmir, through which travellers communicated with this country, is called by the natives To-bhot (written stod-bod) or "High Bod" or "Tibet." Physical Geography.—Almost all the country from the south of the Takla-makan desert to the Himalaya was formerly included under the name of Tibet in general usage. The Kuenlun mts. were, under this scheme, the northern mountains of Tibet; they are in any case the oldest of the great mountain-systems of the Tibetan highland. Their rocks are mostly Lower Palaeozoic and highly metamorphosed, while Mesozoic deposits occur only as land sediments in the valleys of the chain ; this part and the region to the north and north-east have thus apparently been land since Triassic times. To the south of the Kuenlun, Mesozoic deposits become more important, and suggest that the broad zone be tween that chain and the Deccan (part of the ancient Gondwana land) was then largely under water at times, though during the Upper Jurassic phase land conditions prevailed over wide areas.

In the Cretaceous epoch began the great upfolding of the Himalayan region, which probably reached its maximum activity in the Eocene age. Parts of this folding seem to have been directed southward, as is indicated in the Garwhal thrust-plane, but the story is highly complex and there is much penetration of young volcanic rocks, while geysers and hot springs tell the same tale. In the uprise of the younger mountains not only did great fault-lines appear in the south and east of the Tibetan highland, but also the Kuenlun was much broken, and the old Tarim block to the north of it sank. In several parts of its area the Kuenlun attains a height of 7,000 metres, while, in the west, the peak Mustagh (Murtagh or K5) attains 7,282 metres (23,890 ft.), and is, perhaps, the highest point in the chain, though it has been claimed that there are within it heights of nearly 8,000 metres.

Between the western Kuenlun and the Himalaya is the great dissected highland of the Karakorum. The heights attained in the Karakorum are very great, several summits attaining about 8,000 metres, while K2 is 8,610 metres or 28,25o ft. high.

On the general Tibetan highland the oldest formation exposed is the Upper Jurassic, betraying land conditions followed in the next phase by submersion. The highland seems to pass into the mountain-systems of its periphery and to have a general height of 15,000--16,000ft., the highest point known in this region is about 23,600 feet. There are many fault-lines, thrust lines and hot springs. This plateau of inland drainage, characterized by lakes, mostly salt, and hot springs, is called Chang-t'ang.

The southern rim of the general highland just described is the trans-Himalaya or Hedin range of mountains, the average height of which may exceed that of the Himalaya, though the highest peaks (nearly 24,000ft.) are not so great as those of either the Himalaya or the Karakorum. This great series of mountains was very little known until Sven Hedin explored there.