Altai or Altay (both: ăltĪˈ, äl–, ălˈtĪ, Rus. əltĪˈ) [key], geologically complex mountain system of central Asia; largely in the Altai Republic, Russia, and in Kazakhstan, but extending into W Mongolia (where it is called the Mongolian, or Gobi, Altai), and into N China. In the northeast the Kuznetsk Alatau and the Salair Ridge adjoin the Altai and enclose the Kuznetsk Basin. The Russian Altai are bounded by the Sayan range in the west, the Mongolian Altai in the south, and the Tannu-Ola range in the east. The highest sections of the Russian Altai are the Katun, the Chuya, and the Sailyugem ranges. The highest peak in the Russian Altai, Belukha (14,783 ft/4,506 m), is in the Katun range. Meltwater from extensive glaciers feeds many rivers; the Ob and the Irtysh rise in the Altai. Lake Teletskoye, with an area of 90 sq mi (233 sq km), is the largest of the Altai's more than 3,000 lakes. Rich deposits of gold, silver, mercury, iron, lead, zinc, and copper are found in the mountains, especially in E Kazakhstan. Located in the center of the great Asian landmass, the Altai have a continental climate with a wide annual temperature range and receive c.40 in. (101.6 cm) of precipitation annually. Bears, martens, musk deer, and mountain goats inhabit the mountains. The first Russians entered the area in the 17th cent. and mined silver. In the late 19th cent., piedmont agriculture replaced mining as the main occupation. After the Soviet takeover in the early 20th cent., the area became both an important farming and mining region. Öskemen and Leningor are principal mining and industrial centers. The Mongolian Altai support little agriculture and are economically undeveloped.