The essay discusses such little-researched issues of the history of the Mordovian, Mari and Chuvash peoples as military affairs (organization, number, place in the Russian army and strategies, weapons) and participation in the wars of the Russian state of the 16th-17th centuries. The purpose of the publication is to summarize the materials collected by the author in 2011-2020, and to attract the attention of specialists and a wide range of readers to this topic.