The rulers of Zhao issued the spade money jianzubu since 490 BC in masses. It was cast in two denominations, namely of 1 and of 1/2 jin. The mass production of coins is evidence of a flourishing economy; there was a broad middle class with many merchants in Zhao in the 5th and 4th centuries BC. However, only a very limited number of the Zhao coins survived. At that time China suffered from countless wars: it was the "Warring States Period" (475-221 BC). Many of the coins circulating during that time were melted down and turned into spearheads and other armaments.