Backround. The period of the Great Migration in the periodization of history occupies an intermediate position between the early Iron Age and the Middle Ages. This era is characterized by mass migration, which resulted in formation of a number of peoples previously unknown to historians. Among such were the Volga river Finns. Results. The aim of this article is to examine the extent to which the modern hypotheses correspond to the written and archaeological sources. The first mention of the Finnish peoples of the Volga river – the Mordovians and Mary – in written sources is dated in the era of the Great Migration. Their archaeological sites are represented by the late Dyakovo and ancient Mordovian cultures. The culture of the Ryazan-Oka cemeteries, particular ethnicity of which remains controversial, also belongs to the Volga river Finns. The culture of Muroms and Mari was formed only in the Middle Ages. In the Soviet historiography the accuracy of the written sources on this issue was questioned by ideological reasons. Autochthonous views dominated in the science, their supporters dimineshed the role of migration in the history of the Volga river Finns. The archaeological researches of the monuments of the II–V centuries confirmed the accuracy of the written sources and allowed to clarify the role and place of the Volga river Finns in the events of this era. In the early [German] stage of the era of the Great Migration the Volga river Finns took an active part in the migration, during which the formation of Mordovians and Mari took place. Hun invasion, according to the most researchers, had no significant effect on the peoples of the West Volga
