Altai, the Ghin-shan or Golden Mountains of the Chinese, is the name given to a wild mountainous region which covers the southern parts of Tomsk, in Siberia, and partly extends into Mongolia. It comprises the mountainous border-region of the great plateau of Central Asia, between the Tian-shan and the Sajan Mountains, and consists of two separate parts—the Altai proper, belonging to the Russian empire; and the Great Altai, in Mongolia. The former covers with its numerous intricate chains and their spurs a surface thrice as large as Switzerland. Although occupied by the Russians since the 17th century, its orography and structure are but imperfectly known. A huge mountain-ridge, the Sailughein, which separates Russia from China, is the border-ridge of the Central Asian plateau; it is continued to the SW. as the high but yet unexplored ridge of West Sajan, which fringes the plateau in the basin of the Yenisei. Its summits reach a height of from 7000 to 9000 feet. It is pierced in the SW. by the deep depression of Lake Zaisan, which gives an easy access to the high plateau of Central Asia. A series of no less than three different chains fringes the Sailughein ridge towards the NW. Some of these chains are snow-clad, and their highest summit, Byelukla, reaches the height of 11,000 feet; while the others do not exceed 7500 feet. Granites, syenites, and partly also porphyries covered with crystalline slates, as also with Silurian, Devonian, and Carboniferous deposits, constitute the mountains. Deep and wild gorges, immense glaciers, beautiful alpine lakes (the Teletsk, 1600 feet above the sea), and fertile alpine valleys (like the Bukhtarma Valley, 190 miles long), render the Altai a most attractive alpine region. The valleys on its outskirts are being rapidly colonised by Russian agriculturists (600,000 in 1892), who find an easy living in the fertile soil, and the rich sub-alpine meadows. The gold-washings of the Altai, and its silver, lead, copper, iron, and coal mines, are another source of wealth. Nearly 45,000 Kalmucks, Teleutes, and Kumandintses represent the small remainder of the formerly much denser and more highly civilised population, all of the Ural-Altaic stock. The town of Barnaul (17,180 inhabitants) is the chief centre of administration. See ASIA.
As to the Great Altai—still very little known—it is represented on our maps as a high chain of mountains running from NW. to SE., from Lake Zaisan to the central parts of the Gobi, and bordering in the north the Urumtsi depression. It has been partly explored of late by M. Potanin.