The stages of the creation of a Russian centralized state and the development of the idea of a Holy Orthodox Kingdom («Moscow - the Third Rome») is analyzed in the article. After the fall of the Tartar yoke, the Russian state undertook three tasks: an advance toward the Baltic, the reunification of the Russian lands, and the expansion to the east and south. The author shows the role of the native-born of South-West Rus' in the formation of Moscovite Rus' and later the Russian Empire and in the struggle for the preservation of the Russian Orthodox Church. The influence of those born in the Russo-Vlach Moldavian Duchy in the formation of the Russian Imperial Idea is emphasized.