The Altai Mountains (阿尔泰山脉, Altay Mountains) are a mountain range in Central and East Asia, where Russia, China, Mongolia, and Kazakhstan come together, and are where the rivers Irtysh and Ob have their headwaters. The northwest end of the range is at 52° N and between 84° and 90° E (where it merges with the Sayan Mountains to the east), and extends southeast from there to about 45° N and 99° E, where it gradually becomes lower and merges into the high plateau of the Gobi Desert.

The name "Altai" means in Mongolian "Gold Mountain"; "alt (gold) and "tai" (suffix - "with"; the mountain with gold) and also in its Chinese name, derived from the Mongol name (Chinese: 金山; literally: "Gold Mountain"). In Turkic languages altin means gold and dag means mountain. The proposed Altaic language family takes its name from this mountain range.

The Altain mountains have retained a remarkably stable climate changing little since the last ice age. In addition the mix of mammals has remained largely the same - with a few exceptions such as extinct Mammoths - making it one of the few places on earth to retain an ice age fauna.

A movie on Altai region (in Russian):