For over 1,000 years, chariots were indispensable weapons in ancient China. The art of chariot driving and special warfare were used there for longer than anywhere else. Their contribution to the unification of the Chinese empire is undisputed. New archaeological discoveries reveal how the Chinese developed and perfected this sophisticated weapon. In the Bronze Age, over 3,000 years ago, chariots and other war equipment arrived in China from Central Asia via the Hexi Corridor. In addition to trade and new alliances, their spread was mainly due to the Zhou dynasty's incessant military campaigns against rebellious vassal states and the constant attacks by the mobile cavalries of its northern neighbors. Manned with spearmen or archers, the chariots were a decisive weapon in battle.