The paper represents an analyses of the Oirad-Kalmyk language functioning in various historical, social, geographical, economico-political conditions. Nowadays the Oirad-Kalmyks live in different regions of the world (Russia, China, Kyrgyzstan, the USA etc.). The Kalmyk language belongs to the west branch of Mongolian languages (Altaic language family). The Old-Kalmyk writing “Todo bichg” (Clear writing) was worked out in 1648. The UNESCO “Red book of endangered languages” identifies Kalmyk as language in danger of extinction. Language and culture assimilation occurs under the influence of social factors such as heteroethnic environment, demographic factor of the ethnos in the given society. The article is aimed to find out the evolution of the language identity of its native speakers, to define whether the language is able to develop in heteroethnic environment, to specify the role of demographic capacity, communicative capacity of the language and language vitality.