Mammal population of the northwestern Altai included residents, autochthonous species, cosmopolitans, and migrants. The last clearly indicate biogeographical relationships of the biota of the Altai Mountains in the Pleistocene. Most of them penetrated into the Altai from the south. The majority of ungulates and rodents migrated from Central Asia. Yak, red dog, and snow leopard came from the Himalayas, Pamir, and Tien Shan. The natural environment of the Altai Mountains in the Pleistocene enabled migrations of these mammals from the south to north. The same opportunity was true of the ancient man. It is possible to assume that humans migrated from southeastern Asia and Indochina along the eastern foothills of the Himalayas and Nan Shan Mountains to the northwest, to the Zaisan Depression and Altai. This resulted in inevitable exchange of gene material of Paleolithic human populations of southeastern Asia and the Altai.