Focusing on diverse nationalisms, regionalisms, and imperialisms, the book traces the making of the Russian Far East as a new region that found its political form in the Far Eastern Republic (FER) during the Russian Empire/Soviet Union transformation. The nationalisms under study include discourses and policies of imagining and mobilizing Russians, Buryat-Mongols, Koreans, Ukrainians, and other groups in the Russian Far East. The discussion of imperialisms explores Japanese and American attempts to include the region in their spheres of influence, as well as the legacies of Russian expansionism in North and East Asia and the Bolshevik efforts in exporting the revolution to Mongolia, Korea, China, and Japan and possibly turning them into Soviet dependencies. The regionalisms in question were the various projects of imagining distinct Siberian and Far Eastern communities as potentially independent or as part of the heterogeneous Russian nation. Although the regionalisms and imperialisms were important for the making of the FER, it was Russian imperial and post-imperial nationalism formulated in state-centered defensive terms which played the central role in the establishment and abolition of the republic in 1920–1922 and the consolidation of the Russian Far East as a region in the Soviet imperial formation.