The emperor Wang Mang changed the coinage of the realm four times in only seven years, reintroducing a number of older coin shapes such as the spade and knife. This particular example combines two different shapes: the knife and the more familiar round coin with square center hole. The inscription is especially worthy of note. The first two characters - "yi dao" or "one knife" - are inlayed with gold. The rest of the inscription reads "ping wu qian," or "equals five thousand," and sets the value of the coin.

This inscription reflects one of Wang Mang's many reforms related to coinage. Previously coins were assigned a value equal to that of the metal from which they were minted. Wang Mang's policy of assigning arbitrary values to his coinage was probably adopted to reduce the amount of metal tied up in the circulation of money both inside and outside of the realm, for Chinese coins were also used in the city-states beyond the western frontier. Ultimately these reforms were revoked, but it was this sort of experimentation that eventually led to the invention of paper money during the Tang Dynasty (618-907 CE).