The Altai 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, 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.