The book summarizes more than thirty years of expeditionary research by the author. A. Mikulich offers his view on the problem of anthropogenetic relations between East Slavic ethnic groups. The influence of the environment and the ecological-anthropological relationship, which developed in the process of ethnogenesis of Belarusians for more than a hundred generations, are considered. The work was carried out in the Department of Anthropology and Ecology of the Institute of Art History, Ethnography and Folklore of the National Academy of Sciences of Belarus.