The article explores the ideology of national movements in the present day Mordovia republic of the Russian Federation. The author focuses on two cases of nationalism, namely the Mordovian and Erzy ones, analyzing the use of ethnocentric visions of history (myths) as the basis for political claims. The research of ethnocentric myths is based on newspapers and publications of the respective national movements. The author finds out certain similarity in character of ethnocentric myths of both cases of nationalism, suggesting, however, that the two movements differ in their vision of the constituent element of the titular nationality’s republic. Whereas the Mordovian national movement stresses the unity of two ethnic groups (Moksha and Erzy) on the territory of the republic and favors their convergence through fostering of the common Mordovian language and enhancement of the titular nationality’s rights, the Erzy national movement rejects the notion of the Mordovian nationality and strives to promote separate a Ezry language and nationality with consequent claims for separate titular nationality and administrative unit.