ENThe article is devoted to the analysis of the ethnonyms of the Baltic peoples found in ancient Russian chronicles. Based on the analysis of historical information and geographical features of the settlement area, it was established that ethnonyms were originally demonyms. The names of the ancient peoples who participated in the ethnogenesis of the Lithuanians and Latvians reflected the characteristics of the area and appeared in the Baltic-speaking environment. Keywords: Baltic states, Curonians, Latgalians, Latvia, Lithuania, Samogitians.