The Mystery of a Chingissid Called Mamai

There are names of the heroes of different wars that are inscribed on the walls of the main temple of the glory of Russian weapons - the St. George’s Hall of the Kremlin. Among them, there is a single Kazakh surname. Yes, and what! Gubaydulla-Sultan-Genghis Khan. Who was this officer? In what event that was important for Kazakhs was he involved?

And why it was believed among people, that steppe princes can become an obstacle?