The Black Shields — John Maddox Roberts

Long ago, so legend says, the world was destroyed, and everything changed. Once there were animals called bull, and bear; now men ride horned cabos, and avoid the deadly long-neck. Now there are new nations, new empires, for the hearts of men have changed little. In this world, Hael, Shasinn warrior exiled from his home islands for breaking a taboo, has found a life among the nomadic tribes of the plains, but his past is coming to find him. The Shasinn have changed and an old enemy is leading them to conquest. The Black Shields are coming, and the civilized world rocks on its foundations.