Evfimii Fedorovich Karsky (1861-1931) was an outstanding Belarusian philologist, ethnographer and paleographer, the author of the fundamental work “Belarusians”, consisting of three volumes published in the period from 1903 to 1922. This work is considered an encyclopedia of Belarusian studies and covers a wide range of issues related to the language, literature and culture of the Belarusian people. Structure and content of "Belarusians": Volume I (1903): Introduction to the study of language and folk language. Volume II (1908-1912): The language of the Belarusian tribe. Volume III (1916-1922): Essays of the Vocabulary Belarusian tribe. The third volume, Essays on the Literature of the Belarusian Tribe, consists of three parts: Folk poetry (1916): Dedicated to oral folk art, including songs, fairy tales, proverbs and other genres of folklore. Old West Russian Writing (1921): Considers ancient written monuments created in the territory of Western Russia, their linguistic and literary features. Literature in the vernacular language (1922): Analyzes the development of Belarusian literature in the vernacular language, its genres, themes and representatives. Karsky’s work is an invaluable contribution to the study of Belarusian culture and still retains its scientific and ideological relevance. It will be useful for philologists, historians, ethnographers and anyone interested in the history and culture of Belarus. E.F. Karskogo "Belorusses" thus remains a key source for studying Belarusian culture, language and literature.