Long-term soil research efforts (1980–2017) in the Baikal drainage basin revealed a widespread occurrence of thin layers of skeletal soils in the tundra zone: peat-lithozems, lithozems coarse humus and humic and dark-humus, and petrozems. A variety of full-height soils is represented by podburs, peat-podburs, podburs gleyic, podzols and gleysols. It is determined that the soil cover of the mountain-taiga zone is nonuniform because of the manifestation of the vertical zonation, slope aspects and permafrost of different types. The main background of the Khangai soils consists of cryosols and podburs; Khentii — sod-podburs and dark-humus soils; near Lake Khövsgöl — cryosols, podburs and sod-podburs; the Baikal region — podburs, podzols, peat-podburs and sod-podzols, and on the windward slopes of the mountain ridges facing Baikal — podburs and coarse humus burozems. The occurrence and development of burozem soils in the Baikal region is confirmed. In the forest-steppe zone of Hangai and Khentii, the soil diversity is presented by cryosols, sod-podburs, dark- and gray-humus soils, and in the forest-steppe contact zone — chernozems and castanozems. It is established that in the Selenga middle mountains, the basis for soil cover is provided by sod-podburs, and the accompanying soils are gray metamorphic, light-humic and cryoarid soils. We identified a new type of soils, cespitose-gray soils. Psammozems and light-humic soils occur on sands. Chernozems prevail in the steppe zone, and castanozems, cryoarid and, light-humic soils are dominant in the arid steppe zone. It is determined that the floodplain develops soils of different types: immature, alluvial and halophytic. A study is made of the specific character of floodplain soil formation determined by the mountains on the territory, the regional features of floodplain-alluvial processes, the extremely continental climate, and by the functioning of soils in conditions of the combined manifestation of cryodization and aridization. It is emphasized that the 1:5 000 000 soil map of the Lake Baikal drainage basin was created using a unified methodological framework and a unified classification by soil scientists of Russia and Mongolia. It is established that the soils of the Baikal region differ from the soils located at the same latitude of the European territory of Russia. It is found that the mountain zonality has a determining influence on the formation and spatial distribution of soils.Keywords: soil diversity, distribution patterns, natural zones, Lake Baikal drainage basin, cross-border territory of Russia and Mongolia.