Siege of Bilyar

During the rule of Khan Altynbek Alan, an internal political struggle developed between him and Ghazi-Baraj Burundai for the rulership of Volga Bulgaria. To overthrow the khan, Ghazi-Baraj Burundai formed an alliance with one of the Mongol khans. Accordingly, in 1236 the claimant to the throne of the Volga kingdom, Ghazi-Baraj Burundai, attacked Volga Bulgaria's borders together with 200,000 Mongol troops. The initial battle lasted twenty days, ending in a Mongol victory. The Bulgar troops retreated. Khan Altynbek had no choice but to shut himself inside the capital of the time, Bilyar. A forty-five-day siege followed.

The city held out for forty-five days, but the Mongol troops eventually broke through and captured it. Altynbek was killed when the city fell. His daughter Altynchan managed to escape with a battalion and the commander Bichman. The two led the anti-Mongol struggle, which by this stage was also directed against Ghazi-Baraj Burundai. Ghazi-Baraj Burundai proclaimed himself ruler of Volga Bulgaria and moved the capital to Suvar. Volga Bulgaria became dependent on the Mongol Empire. Ghazi-Baraj Burundai managed to preserve some of the country's autonomy but lost territories in the south.