 These tokens came to be used as media of exchange themselves and were known as spade money and knife money.As standard circular coins were developed following the unification of China by Qin Shi Huang, the most common formation was the round-shaped copper coin with a square or circular hole in the center, the prototypical cash.The early Ban Liang cash coins were said to have been made in the shape of wheels like how other Ancient Chinese forms of coinage were based on agricultural tools.