The Mongol invasions of the thirteenth century perhaps called a halt to the advance of East Slav venturers along the mid and upper Volga; Nizhnii Novgorod had been founded in 1221, but expansion and colonisation seems subsequently to have been retarded. In the second half of the fourteenth century, however, when there is much other evidence of a general Russian recovery, Vyatka was seized – from about 1375 it was a Russian base in the centre of a rich fur-getting area. Russian settlements arose south of Nizhnii Novgorod in the Sura basin and contact was established with the Chuvash (though they were not yet distinguished as such by the Russians). The Sura long remained a frontier or contact zone for Russians and Chuvash.

In the mid and late fifteenth century Russian princes were sometimes in alliance with, but often in conflict with, the Kazan' khanate which was formed in 1445; the population of the khanate was mainly Tatar, but included Chuvash, a Turkic people, and some other groups (Mari, Udmurts) of Finnish stock. These complicated and obscure relations are associated with the dynastic struggles both of the Russian princes themselves and, on the other hand, of the Tatars during the decline of the Golden Horde. These relations were further complicated by the existence of the Crimean khanate, and behind it the Turkish sultan, in the south and by Polish and Lithuanian efforts to use the khanates as allies against Moscow.