Misfits and Heroes — Kathleen Flanagan Rollins

A thief offers a woman a chance at a new life by cutting her bonds, beginning a journey that will take both of them downriver and out to the coast of West Africa. The time is 12,000 BC, and war is breaking out between the villages on the coast. Frantic to escape, the two travelers join others fleeing the chaos of battle. They think they'll be safe if they head down the coast by boat, but the sea sweeps them out into a new, very different world and a destiny they couldn't have imagined.