AUTIIORITIES  .—See N . M . Przhevalsky,

Mongolia, the Tangut Country, &c . (Eng. trans., ed. by Sir H . Yule, London, 1876), and From Kulja across the Tian Shan to Lob Nor (Eng. trans. by Delmar Morgan, London, 1879) ; G . N . Potanin, Tangutsko-Tibetskaya Okraina Kitaya i Centralnaya Mongoliya, 1884-1886 (1893, &c.); M . V . Pjevtsov, Sketch of a Journey to Mongolia (in Russian, Omsk, the sand-dunes cross over to the left bank of the Hwang-ho, and are threaded by the beds of dry watercourses, while the level spaces amongst them are studded with little mounds (3 to 6 ft. high), on which grow stunted Nitraria Scoberi and Zygophyllum . Ordos, which was anciently known as Ho-nan (" the country south of the river ") and still farther back in time as Ho-tau, was occupied by the Hiong-nu in the 1st and 2nd centuries A.D., but was almost de-populated during and after the Dungan revolt of 1869 . North of the big loop of the Hwang-ho Ordos is separated from the central Gobi by a succession of mountain chains, the Kara-naryn-ula, the Sheitenula, and the In-shan Mountains, which link on to the south end of the Great Khingan Mountains . The In-shan Mountains, which stretch from 108° tc 112° E., have a wild Alpine character and are distinguished from other mountains in the S.E. of Mongolia by an abundance of both water and vegetation .

In one of their constituent ranges, the bold Munni-ula, 70 m.

long and nearly 20 m. wide, they attain elevations of 7500 to 8500 ft., and have steep flanks, slashed with rugged gorges and narrow glens . Forests begin on them at 5300 ft. and wild flowers grow in great profusion and variety in summer, though with a striking lack of brilliancy in colouring . In this same border range there is also a much greater abundance and variety of animal life, especially amongst the avifauna . Eastern Gobi.—Here the surface is extremely diversified, although there are no great differences in vertical elevation . Between Urga (48°N. and 107°E.) and the little lake of Iren-dubasu-nor (111 °5o' E. and 43° 45' N.) the surface is greatly eroded, and consists of broad flat depressions and basins separated by groups of flat-topped mountains of relatively low elevation (50o to boo ft.), through which archaic rocks crop out as crags and isolated rugged masses . The floors of the depressions lie mostly between 2900 and 3200 ft. above sea-level . Farther south, between Iren-du'basu-nor and the Hwang-ho comes a region of broad tablelands alternating with flat plains, the latter ranging at altitudes of 3300 to 3600 ft. and the former at 3500 to 4000 ft . The slopes of the plateaus are more or less steep, and are sometimes penetrated by " bays " of the low-lands . As the border-range of the Khingan is approached the country steadily rises up to 4500 ft. and then to 5350 ft . Here small lakes frequently fill the depressions, though the water in them is generally salt or'brackish . And both here, and for 200 M. south of Urga, streams are frequent, and grassgro.wsmoreorlessabundantly . There is, however, through all the central parts, until the bordering mountains are reached, an utter absence of trees and shrubs .

Clay and sand are the predominant formations, the watercourses, especially in the north, being frequently excavated 6 to 8 ft. deep, and in many places in the flat, dry valleys or depressions farther south beds of loess, 15 to 20 ft. thick, are exposed . West of the route from Urga to Kalgan the country presents approximately the same general features, except that the mountains are not so irregularly scattered in groups but have more strongly defined strikes, mostly E. to W., W.N.W. to E.S.E., and W.S.W. to E.N.E . The altitudes too are higher, those of the lowlands ranging from 3300 to 5600 ft., and those of the ranges from 650 to 165o ft. higher, though in a few cases they reach altitudes of 8000 ft. above sea-level . The elevations do not, however, as a rule form continuous chains, but make up a congeries of short ridges and groups rising from a common base and intersected by a labyrinth of ravines, gullies, glens and basins . But the tablelands, built up of the horizontal red deposits of the Han-hai (Obruchev's Gobi formation) which are characteristic of the southern parts of eastern Mongolia, are absent here or occur only in one locality, near the Shara-muren river, and are then greatly intersected by gullies or dry watercourses.' Here there is, however, a great dearth of water, no streams, no lakes, no wells, arid precipitation falls but seldom . The prevailing winds blow from the W. and N.W. and the pall of dust overhangs the country as in the Taklamakan and the desert of Lop . Characteristic of the flora are wild garlic, Kalidium gracile, wormwood, saxaul, Nitraria Scoberi, Caragana, Eph'dra, saltwort and dirisun (Lasiagrostis splendens) . This great desert country of Gobi is crossed by several trade routes, some of which have been in use for thousands of years . Among the most important are those from Kalgan on the frontier of China to Urga (boo m.), from Su-chow (in Kan-suh) to Hami (420 m.) from Hami to Peking (1300 m.), from Kwei-hwa-cheng (or Kuku-khoto) to Hami and Barkul, and from Lanchow (in Kan-suh) to Hami . Climate —The climate of the Gobi is one of great extremes, combined with rapid changes of temperature, not only at all seasons of the year but even within 24 hours (as much as 58°F.) . For instance, at Urga (3770 ft.) the annual mean is 27.5°F., the January mean -15.7°, and the July mean 63.5° the extremes being 100.5° and -44.5 while at Sivantse (3905 ft.) the annual mean is 37° the January mean 2.3°, and the July mean 66.3°, the range being from a recorded maximum of 93° to a recorded minimum of -53° . Even in southern Mongolia the thermometer goes down as low as -27°, and in Ala-shan it rises day after day in July as high as 99° .

Although the south-

east monsoons reach the S.E. parts of the Gobi, the air generally throughout this region is characterized by extreme dryness, especially during the winter . Hence the icy sandstorms and snow-storms of spring and early summer . The rainfall at Urga for the year amounts to only 9.7 in . r Obruchev. in Izvestia of Russ . Geogr . Soc . (1895) . x In Tangutsko-Tibetskaya Okraina Kitaya i Centralnaya 1l~Pngoliya, i. pp . 96, &c . ' See Sand-buried Cities of Khotan (London, 1902) . 1883); G . E .

Grum-Grzhimailo, Opisanie Puteshestviya v Sapadniy Kitai (1898-1899) ; V . A . Obruchev, Centralnaya Asiya, Severniy Kitai i Nan-schan, 1892-1894 (1900-1901); V . I . Roborovsky and P . K .

Kozlov, Trudy Ekspeditsiy Imp . Russ . Geog . Obshchestva Po Centralnoy Asiy, 1893-1895 (1900, &e.); Roborovsky, Trudy Tibetskoi Ekspeditsiy, 1889-189o; Sven Hedin, Scientific Results o a Journey in Central Asia, 1899-1902 (6 vols., 1905-1907) ; Mutterer, Durch Asien (1901, &c.); K . Bogdanovich, Geologacheskiya Isledovaniya v Vostochnom Turkestane and Trudiy Tibetskoy Ekspeditsiy, 1889-189o; L. von Loczy, Die wissenschaftlichen Ergebnisse der Reise des Grafen Szechenyi in Ostasien, 1877-1880 (1883); Ney Elias, in Journ . Roy .

Geog . Soc . (1873) ; C . W .

Campbell's " Journeys in Mongolia," in Geographical Journal (Nov . 1903); Pozdnievym, Mongolia and the Mongols (in Russian, St Petersburg, 1897 &c.); Deniker's summary of Kozlov's latest journeys in La Geographic (1901, &c.) ; F. von Richthofen, China (1877) . (J . T .