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. It was also an important resting and trading place for traders from the North who traveled along the river to Volga Bulgaria. The Mongol invasion of Volga Bulgaria was a serious blow to the region. Kozmodemyansk was founded by Tsar Ivan the Terrible in 1583 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. The fortress was named after Sts. Cosmas and Damian. For many years the streltsy fortress was the only building in the area. Chapel As commerce along the Volga developed, a town gradually grew around the fortress, but the region remained largely populated by the Mari people. The town had a fair specializing in wooden and wicker ware goods produced by local craftsmen. The town was very active during summer, but winters brought a halt to river traffic. In the 19th century, Kozmodemyansk was a more important trading place along the Volga than the neighboring towns of Vasilsursk and Cheboksary. It was a typical halfway "overnight" stop for the Volga River steamers between Nizhny Novgorod and Kazan. In the 20th century, the town developed industrially. According to the official Imperial Russian statistics, on January 1, 1913, the population was 5,500, of which 97.5% were Russians. In 1918, there was a dispute between Mari and Chuvash representatives of Kozmodemyansk in the Idel-Ural Movement. It was not decided to which proposed state 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 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].
A local museum was opened in 1919 and now contains paintings by many Mari and Russian artists. A regional museum to preserve artifacts of the Mari culture was opened in 1979. An open-air ethnographic museum opened in 1983. It contains over sixty varied buildings typical of Russian/Mari culture. They house over 2,000 exhibits of artisan craft and tools. Even the variety of fences around the grounds display typical Mari designs.
