These flat coins made of bronze resemble knives. They are believed to have been minted and circulated in the state of Yan, located in Hebei province, during China’s Warring States period. They are also known as “Ming” knife coins due to the character “明 (ming)” rendered onto the surface of the coin that resembled the daily necessity that was the knife. They are usually found in bundles, their numbers ranging from the tens to thousands, in wooden boxes or jars buried in pits.