For this, the Bashkirs were being obliged to pay yasak (tribute) (in the beginning with furs and honey, later on with dollars). In 1573, the Bashkirs uncovered it inconvenient to pay for yasak in Kazan and questioned the Russian tsar to make a city for them on their own land https://ufabnb80368.mdkblog.com/35540180/detailed-notes-on-ufa