The Mongols inhabited an area to the north of China.
The most famous Mongol leader was Genghis Khan. He was the leader of a destitute clan who prevailed in an inter-clan feud. He overcame all rivals and by 1206 was acknowledged as Genghis Khan (Universal Ruler) of all Mongolian people.
He subjected China, devastated Khwarezm (Uzbekistan) and became the creator of the Mongol nation and founder of one of the vastest empires in world history which stretched from Northern China to the Black Sea.
After the death of Genghis Khan the Empire was divided between his four sons.
www link :
The Medieval Sourcebook:
13th century text about the Mongols