The author publishes the results of studies of trade contacts between the Volga Bоlgars and Mordvins in the 10^th – early 15^th centuries. First of all, coin hoards are investigated, the number of coins found in burial grounds, as well as household items and inscriptions indicating the presence of trade contacts between the Bulgars, Tatars and Mordvins are analyzed. The findings of metal boilers and kettles among the Finno-Ugric peoples, primarily the Mordvins, who performed a sacred function, and their place in trade are analyzed. In addition, some data from written monuments are given, for example, "Tale of Bygone Years". Based on these sources, a comprehensive analysis of the changes in trade contacts between the Bulgars and Mordvins during the times of Volga Bоlgaria and the Golden Horde is carried out, data on their evolution, an increase in trade volumes and the reasons that led to this are given, a general description of the processes is given.