This chapter examines the ethics of war in Ancient China, focusing specifically on the development of Warring States political philosophy. It argues that the development of humanitarian values originated in the formation of the sovereign states system during the Warring States period. As states arose, they increasingly relied on peasant labor for agricultural resources and miltiary expeditions, which led to the development of political and moral ideas that reflected theinterests of ordinary people. Political theorists from the major intellectual schools (e.g., Confucianism, Taoism, and Mohims) developed humanitarian ideas as a way of reflecting the interests of the people. Throughout, it examines textual evidence that shows that humanitarian ideals shaped how Warring States theorists approached issues of war and peace.