During the Warring States period there was constant conflict and competition between the various states.  Lavish and public displays of wealth was one way for a ruler to assert his prestige before his allies and rivals.  The wealth of the state of Zeng can only be imagined, but the tonnage of the bronzes in Marquis Yi's tomb far exceeds that of any ancient tomb anywhere in the world -- the total weight is estimated at over ten metric tons.