Abstract. The article presents a generalized analysis of the published national historical and theoretical historiography of the process of establishing the territorial and demographic traditions of the Chernihiv-Siverskyi population as part of Kyivan Rus. The territory of their settlement, demographic composition, evolution of the life and lifestyle of the northerners, which have become common traditions of the Indo-European peoples, are determined. The research methodology is based on the heuristic method of systematization of classical and modern scientific thought, historical, geographical, artistic historiography and archaeological sources, which formed the cultural direction of systematization of the reconstruction of the holistic process of the problem. The main historiography to the topic was compiled by the editions of the classics of the historical school, which laid down the fundamental knowledge of social history and culture: from ancient times to medieval Ukraine-Rus, of which the Chernihiv-Siverskyi region was a component. An attempt is made to generalize the theory and historical practice of the transformation of the socio-cultural traditions of the Ukrainian population of the South-Eastern region on the basis of the created all-European and nationally original traditions of Ukraine-Rus. They laid common foundations for the life and livelihood of local tribes, the development of territories, agriculture, public organization, customary law, financial and trade relations, diplomacy, spiritual, cultural and artistic life. Because of the evolution of the development of the components of the Ukrainian nation, a historical transformation and socialization of the transmission of the main spiritual values from paganism to сhristianity took place. On these foundations, the national traditions of consolidating land allotment principalities – Kyiv, Chernihiv, Siver, etc. – have formed and entrenched; hereditary dynasties of the Riurykovych family, in particular the Chernihiv Olhovych, Davydovych; the corresponding composition of the population, characterized by the local climate, flora, fauna, which influenced the character and spirit of the people, proper names - ethnonyms, toponyms, hydronyms.