Before proceeding to define the three great basins into which China may be divided, it will give a better idea of the whole subject to speak of the mountain ranges which lie within and near or along the limits of the country. The latter in themselves form almost an entire wall inclosing and defining the old empire; the principal exceptions being the western boundaries of Yunnan, the border between Ílí and the Kirghís steppe, and the trans-Amur region. Commencing at the north-eastern corner of the basin of the Amur above its mouth, near lat. 56° N., are the first summits of the Altai range, which during its long course of 2,000 miles takes several names; this range forms the northern limit of the table-land of Central Asia. At its eastern part, the range is called Stanovoi by the Russians, and _Wai Hing-an_ by the Chinese; the first name is applied as far west as the confluence of the Songari with the Amur, beyond which, north-west as far as lake Baikal, the Russians call it the Daourian Mountains. The distance from the lake to the ocean is about 600 miles, and all within Russian limits. Beyond lake Baikal, westward, the chain is called the Altai, _i.e._, Golden Mountains, and sometimes _Kin shan_, having a similar meaning. Near the head-waters of the river Selenga this range separates into two nearly parallel systems running east and west. The southern one, which lies mostly in Mongolia, is called the Tangnu, and rises to a much higher elevation than the northern spur. The Tangnu Mountains continue under that name on the Chinese maps in a south-westerly direction, but this chain properly joins the Tien shan, or Celestial Mountains, in the province of Cobdo, and continues until it again unites with the Altai further west, near the junction of the Kirghís steppe with China and Russia. The length of the whole chain is not far from 2,500 miles, and except near the Tshulyshman River, does not, so far as is known, rise to the snow line, save in detached peaks. The average elevation is supposed to be in the neighborhood of 7,000 feet; most of it lies between latitudes 47° and 52° N., largely covered with forests and susceptible of cultivation.