The Warring States period

The remnants of the Zhou order collapse: a dozen and a half kingdoms swallow one another until seven great ones remain. Wars are no longer chariot duels of the nobility but conscript armies of tens of thousands, with crossbows, iron weapons and long sieges; borders are walled off with long ramparts. At the same time rulers bid for advisers, and rival schools appear: the Confucians; the Mohists with their preaching of universal love; the Legalists demanding harsh uniform rules for all. In this age too takes shape the treatise on war ascribed to Sunzi.