The article is an analytical review of the scientific works of the famous Tuvan researcher, Candidate of Philosophical Sciences, Honored Worker of the Republic of Tuva, a historian, ethnosociologist and ethnopolitologist Mongush Sendazhievich Bayyr-ool (1939-2021), dedicated to his 85th anniversary. The purpose of the article is to study the main scientific works of Mongush Bayir-ool on the basis of a bio-bibliographic index compiled with his own participation in 2019. The author provides a brief biographical information about him, as well as highlights the main topics of his research: ethnography of Tuvan nomads, ethnopolitology and political history of Tuva, biographies of Tuvan politicians and the chronicle of political repression in Tuva. The author highlights the biography of Salchak Toka (1901-1973), since Mongush Bayir-ool had a particular interest in this debatable guestion. His works acquire additional historiographical and source-based value. In general Mongush Bayir-ool’s scientific heritage represents a unique and rich reservoir of materials for historians, ethnographers, sociologists and political scientists studying the history of Tuva in accordance with the main themes of his scientific works.