Kubilai Khan is perhaps the most known Mongol leader after his grandfather, Genghis Khan.  He is known for the direction and building of a magnificent estate in Inner Mongolia intended to be a summer capital or palace.  The estate is also known as Xanadu in western parlance.  

Kubilai is also notable for his final conquest over the Southern Sung Dynasty in China. The eleven-year slog through China finally ended in the collapse of the Dynasty in 1279.  The campaign featured the longest known siege in Chinese history.  The five-year siege of Xiangyang, China finally broke in favor of the Mongols with the use of the trebuchet.  These weapons had originated in China many centuries before that time. It had made its way to the west and Europe, and Kubilai Khan brought it back to China, and improved and used it in the conquest of the Sung Dynasty. Kubilai Khan united China once again after the defeat of the Sung Chinese.