The majority of the Mongol cavalry consisted of the tribesmen, who were only yesterday conquered by Genghis Khan, not only of the Mongol origin but also Manchu, Turk and Tungus origin. But why they showed so a high degree of obedience to their commanders and won battles after battles in alien territory far from their motherland in hostile environment, conquering numerically superior nations? After the death of Genghis Khan his grandson Batu was given only 4000 cavalrymen and Batu raised an army of hundred thousand soldiers from the conquered territories to fight and defeat the Russian kingdoms and European countries. Only the death of Great Khan Ogodei was the reason for his return to Mongolia. According to the common logic his army must have revolted against him and killed the negligible amount of Mongol cavalrymen, half of which were left behind to guard the headquarters. But they did not revolt, rather they fought with dedication to put their conqueror in control of Russia and Europe. The only possible explanation is that the tribesmen identified themselves with the nomad Mongols and the settled population of Russia and Europe were alien to them more than their suzerain Mongols.

The tribal community, divided by the language and origin, had one unified identification in the way of living, cultural heritage and technology. During the great Empire many scholars from the conquered nations were working the academies of sciences founded by the Mongol rulers, thus enriching the knowledge of the Mongols by the achievement of other civilizations. It was the Mongols, who introduced paper currency to the world, it was the Mongols, who brought canon to Europe, it was the Mongols, who laid down the principles of the modern postal system. The cultural achievements of the Mongols were enriched by the achievement of the other settled civilizations.

Already from the third generation of the Mongol rulers the Mongols lost their single cultural identity, some of them adopting Islam, some Christianity, some Buddhism etc. The feeling of national unity and identity was still high, as when the soldiers of Khubilai Khan refused to fight against provincial ruler Khaidu on the ground that they did not wish the slaughter of their fellow countrymen, but the religious and cultural alienation was stronger. So Muslim rulers of Central Asia were fighting against the Christian Mongols settled in Russia and the discipline which united the Mongols fell down and the Mongols started to fight against each other. The Mongol Empire as a single unit came to its end and the Mongols settled abroad were absorbed by the local population in the absence of their own identity and from the past glory of the Empire only nostalgia of belonging to the Great Genghis Khan continued merely as a slogan. By the fourteenth century the last Mongol Empire in China Yuan Dynasty had fallen and the outnumbered and alienated Mongol tribes had to confine themselves again to the Steppe region of Mongolia.

http://www.ignca.nic.in/ls_03011.htm Crisis of Cultural Identity in Mongolian Nomadic Civilization