The contemporary system of international relations is undergoing profound changes that affect the humanitarian, cultural, and religious dimensions of world politics. The relevance of the topic addressed in this article is also determined by the emergence of new models of interaction between the state and religious communities in a postsecular context. Particular attention is paid to how religious ideas, institutions, and communities influence the development of interstate relations, as well as the formation of cultural, political, and diplomatic practices in Inner Asia. The purpose of this article is to examine the influence of Buddhist ideas and institutions on Russian-Mongolian relations, historically and currently. For over three centuries, Buddhism has exerted a certain influence on the formation of the Russian state’s foreign policy in the East. Several stages in the transformation of the role of Buddhism and Buddhist communities can be identified, characterized by the generally peripheral significance of Buddhism in interactions with state institutions and the significant influence of changes in Russian state policy on the development of Buddhist communities.