The horse-drawn chariot used during the late Shang dynasty (c. 1100 BC) excavated at the Ruins of Yin in Anyang, Henan. The use of chariots in warfare meant that battles were conducted over the plain between armies of highly organized states. These facts indicate that the Yellow River delta at the time was sufficiently free of floods as to allow many states of great wealth to coexist on its bounty.