Wikipedia
Puresh was a Moksha kanazor (king), ruler of the Murunza kingdom in the Middle Volga region. He was ally of Russian Grand Prince Yuri II and of Cuman Khan Köten against the Volga Bulgars and Erzyas in the 1220s. In September 1237 the Mongols invaded Murunza and Puresh was forced by Jebe and Sübötäi to join the Mongols in their European campaign. Puresh's warriors became the vanguard of the Mongol army and took part in the seizure of Kiev, Sandomierz and Zawichost. Puresh secretly met with Henry II the Pious one day before the Battle of Legnica and they agreed that the Moksha army would join the Silesian and Greater Poland troops. Subutai revealed the plot and Puresh, his son Atämaz and many Moksha warriors were killed sleeping after midnight of 9 April 1241.