What is "bilars"

Bilars were medieval (10th-13th centuries) Turkic tribe's commonwealth in the Middle Volga. The Bilars are known to have founded the city of Bilär. Since the 10th century they were a part of Volga Bulgaria. In the 11th-14th centuries their land (today's Alexeyevsky District of Tatarstan) was one of Bulgaria's emirates or duchies.