The book is dedicated to the 425th anniversary of the voluntary accession of Udmurtia to the Russian state. It characterizes the situation and reasons, reveals the historical significance of this event. The authors show how friendship between the Russian, Udmurt and other peoples developed and strengthened, highlight the historical role of the Great October Revolution, which led the Udmurt people, like other peoples of our country, to true prosperity. For a wide range of readers.