West of Eden

On an Earth where the dinosaurs never died out, two very different intelligent species have divided the world between them: the Yilane, a reptilian civilization built on genetic engineering rather than machines, and the Tanu, Stone Age humans clinging to survival in the north. Kerrick was taken captive as a boy and raised among the Yilane, learning their language and their contempt for humans as 'barely sentient animals' -- but as the planet cools and the Tanu are pushed south into Yilane territory, Kerrick finds himself caught between the two peoples just as war between them becomes unavoidable. Harry Harrison's alternate-evolution epic, opening the Eden trilogy.