Genghis: Birth of an Empire by Conn Iggulden

Conn Iggulden's novels are grand historical tales of conquest and vengeance, cruelty and greatness. Now the acclaimed author of Genghis: Birth of an Empire delivers a masterful new novel of the mighty Mongol conqueror--as Genghis Khan sets out to unify an entire continent under his rule....
He came from over the horizon, a single Mongol warrior surrounded by his brothers, sons, and fellow tribesmen. With each battle his legend grew and the ranks of his horsemen swelled, as did his ambition. For centuries, primitive tribes had warred with one another. Now, under Genghis Khan, they have united as one nation, setting their sights on a common enemy: the great, slumbering walled empire of the Chin.