The book "Ancient Russian nation" is seen during the X-XIII centuries, when the Slavic population of Eastern Europe was a single ethno-linguistic community - Old Russian nationality. On the basis of modern historical and archaeological data, the processes of formation and development of the ethnic group. It analyzes the complex picture of the development of the Slavs of the East European Plain in the early Middle Ages and integration events that led to the unification of various tribal entities into a single entity. It turns out that the historical lands, to which the members of the territory of ancient Russia, were the legacy of the old Slavic tribal differentiation. The historical situation in Eastern Europe in the second half of the XIII-XIV century., Was interrupted by the integration processes that eventually led to the formation of Russian, Ukrainian and Belarusian peoples.