Pre-history
The original populations were Finnic tribes Meshchyora and Muroma, Mordvins. The land was under Kievan Rus' and Volga Bulgaria's influence. Local tribes were tributaries of Russian dukes. Later, the area was incorporated into Vladimir-Suzdal. In 1152, duke of Vladimir Yuri Dolgoruky founded Gorodets-Meshchyorskiy. After the Mongol conquest, the territory was incorporated into the territory of the Golden Horde. Turkic settlers appeared in those areas, and most of them accepted Islam under influence from the Volga Bulgars. The semi-independent principality Mishar Yurt was founded by Hordian Mohammad Shirin beg. From 1393, the area became a part of Russia. After the battle of Suzdal in 1445, Olug Moxammad claimed to return those lands to the Tatars.
According to some historians, such as Khudyakov, Vassily executed the claim and Moxammat's son Qasim was crowned as a ruler of Meshchyora lands. The area and capital were renamed after him. Another version is that Qasim came into Russian service and was granted those lands to create a buffer state between Grand Duchy of Moscow and the Khanate of Kazan. However, the Khanate was a vassal of Russia. From the beginning, Khans governed the Khanate's territory, but the inner politics were controlled by Russia.
Read more about this topic: Qasim Khanate