The article looks at language contacts between the Kalmyk language and the language of Oirats living in Mongolia in the sphere of lexis. The lexical layer analyzed in the article is landscape vocabulary. For comparison, materials from the old-written Mongolian, Khalkha-Mongolian, and Buryat languages were used. The presence of similar words testifies the existence of the so-called general Mongolian layer and once one people separated in time and space.