Eternal sky trilogy

Going into exile after barely escaping a war waged by his cousin and brother, Temur, the grandson and heir of the Great Khan, teams up against an enemy cult with former princess Samarkar, who after a series of bitter betrayals has pursued a life of magical study.

"Re Temur, legitimate heir to his grandfather's Khaganate, has finally raised his banner and declared himself at war with his usurping uncle. With his companions--the Wizard Samarkar, the Cho-tse Hrahima, and the silent monk Brother Hsiung--he must make his way to Dragon Lake to gather in his army of followers. But Temur's enemies are not idle; the leader of the Nameless Assassins, who has shattered the peace of the Steppe, has struck at Temur's uncle...