The Song of Naga Teot Series by Heather Gladney

A swordsman held captive by his oath of vengeance, and a king held captive by his position. Together they would start a war. Together they would free their land, or die. A lethal song of the sword sings across the desert.

As fierce as the desert storms, Naga Teot, last of his clan, has debts to pay. First for the birthright stolen from him, second for his slaughtered family, and third for Caladrunan, Liege Lord of Tan, who by friendship and Great Oath he is sworn to protect. The savage sequel to Teot's War.