Volga Bulgaria wasn't based around Kazan, it was based further south around the cities of Bulgar and Bular, and in Suvar land. Kazan wasn't important until after the Mongol invasion and Bulgar lands were overrun by Tatars, and Bulgar, Suvar, and Mordvin refugees fled north. Calling a Volga-Bulgarian army "Kazan army" is just wrong. The Kazan Khanate was not Volga Bulgaria, it was a remnant of the Mongolo-Tatar Golden Horde based in old Bulgar land.
Volga Bulgaria wasn't based around Kazan, it was based further south around the cities of Bulgar and Bular, and in Suvar land. Kazan wasn't important until after the Mongol invasion and Bulgar lands were overrun by Tatars, and Bulgar, Suvar, and Mordvin refugees fled north. Calling a Volga-Bulgarian army "Kazan army" is just wrong. The Kazan Khanate was not Volga Bulgaria, it was a remnant of the Mongolo-Tatar Golden Horde based in old Bulgar land.