[8] Though not attested in any document, the town of Kozmodemyansk was likely preceded by a Mari wooden fortress controlling the confluence of the Volga and the Vetluga Rivers.

Kozmodemyansk was founded by Tsar Ivan the Terrible in 1583[citation needed] after his conquest of Kazan in 1552 and the Cheremis Wars in 1553–1557, 1582, and 1592 as a frontier fortress to guard the new border of the Grand Duchy of Moscow.

As commerce along the Volga developed, a town gradually grew around the fortress, but the region remained largely populated by the Mari people.

[citation needed] It was not decided to which proposed state (Mariland or Chuvashia) the town, as well as the surrounding countryside, should be merged.

A few rare mentions which have remained show that the Volga was to become the border between Chuvashia and Mariland, with considerable cultural and political autonomy (after the example of the status of the Grand Duchy of Finland in the Russian Empire) given to the Hill Mari minority on the south side of the Volga in Chuvashia (according to the preserved papers from the Meeting of Representatives of the Minority Peoples on May 15, 1917 and Idel-Ural State.