The work is devoted to the study of a very little-studied period in the history of the Eastern Slavs - II-V centuries. AD Written sources contain very little information about this time, so an attempt was made to use folklore monuments of the East Slavic and partly Germanic peoples as sources. The first chapter is devoted to substantiating the author's assumption that the prototype of Kashchei (Koshchei) the Immortal - a character in East Slavic fairy tales and epics - is the leader of the Ostrogoths of the 4th century. Germanarich. In the second chapter, these folklore monuments (as well as some monuments of the German epic) are used in comparison with written sources and data obtained as a result of archaeological excavations to restore a broad picture of the society and culture of the peoples who lived in the first centuries of our era on the territory of what is now Ukraine. Appendix to This work is an independent study “On the historical prototype of Hildebrand’s image.” It examines the possibility of having a historical prototype for the hero of the Middle High German epic Hildebrand. The opinion is substantiated that the prototype of Hildebrand was the leader of the Ostrogoths of the 4th century, Hermanaric (Ermenrich), although he was subsequently subjected to significant idealization. The mechanism of formation of different epic heroes from the image of one historical figure is considered: negative ones - for example, the Eddic Jormunrekk and positive - Hildebrand.