Based on published and newly identified archival sources, the book examines the history of the formation and formation of the Chuvash autonomy. The prerequisites, conditions and ripening factors of the Chuvash ideas and projects of national-territorial autonomy are characterized, the activities of national leaders to resolve the issue of the formation of the Chuvash Autonomous Region in 1920 are highlighted. Special attention is paid to the analysis of the large preparatory work of the leaders of the Chuvash Autonomous Region to transform it into an autonomous republic in 1925. Complex issues of the territorial structure of the Chuvash Autonomous Soviet Socialist Republic, the establishment of its borders are considered. The main milestones of the national-state construction of the republic are also traced.