Before the Mongol conquest, Russians of Novgorod and Vladimir repeatedly looted and attacked the area, thereby weakening the Bulgar state's economy and military power.
There is no historical mention except a short account by the Arab historian Ibn al-Athir, writing in Mosul some 1,800 km (1,100 mi) away from the event.
In 1232 the Mongol cavalry subjugated the southeastern part of the Bashkiria and occupied southern portions of Volga Bulgaria.
[1][2] The Mongols besieged and sacked Bilär, Bolghar, Suar, Cükätaw, and most other cities and castles of Volga Bulgaria; killing or enslaving virtually all inhabitants.
The territory was later divided into duchies; each of which eventually received or gained varying levels of autonomy as vassals of the Golden Horde.
After the Mongols left Volga Bulgaria to conquer the Russian land, the Bulgars rebelled, led by the nobility.
The southern steppe areas of Volga Bulgaria may have been settled by nomadic Kipchaks, and agricultural development suffered a severe decline.
Some Bulgarians, primarily masters and craftsmen, were forcibly moved to Sarai and other southern cities of the Golden Horde.
Some historians hypothesize that during the rule of the Mongols, the ethnic makeup of the population of Volga Bulgaria did not change, remaining largely Bulgar and partly Finno-Ugric.