Daughter of Xanadu by Dori Jones Yang (Published by Delacorte Books, January 11, 2011)
Athletic and strong willed, Princess Emmajin's determined to do what no woman has done before: become a warrior in the army of her grandfather, the Great Khan Khubilai. In the Mongol world the only way to achieve respect is to show bravery and win glory on the battlefield. The last thing she wants is the distraction of the foreigner Marco Polo, who challenges her beliefs in the gardens of Xanadu. Marco has no skills in the "manly arts" of the Mongols: horse racing, archery, and wrestling. Still, he charms the Khan with his wit and story-telling. Emmajin sees a different Marco as they travel across 13th-century China, hunting 'dragons' and fighting elephant-back warriors. Now she faces a different battle as she struggles with her attraction towards Marco and her incredible goal of winning fame as a soldier.
This sounds like a really unusual and interesting historical novel, I don't believe I have ever read anything set in Asia during this time period.