During the last 25 years, abundant material on small mammals has been obtained from numerous Pleistocene archaeological sites, caves, and open localities in the Baikal region. Most small mammal fauna localities are dated to Sartan time (23000–10000BP), with some attributed to Karginsk time (50000–23000BP). Paleontological studies provided a considerable amount of information on environmental changes both in Transbaikalia and in the Fore-Baikal region, during Palaeolithic and Mesolithic since the end of Middle Pleistocene.