Bronze banliang coin
From Qin state, China, 3rd century BC
The appearance of round coins in China
The Chinese inscription on this coin reads banliang, with ban to the right of the hole and liang to the left. Banliang means 'half-ounce' - the weight of the coin.
Banliang coins circulated as money in the powerful state of Qin during the violent Warring States period (475-221 BC). In 221 BC the Qin state emerged victorious and founded the new Qin Empire. Qin Shi Huangdi, the first emperor of unified China, also unified the currency, announcing that banliang coins would be standard throughout the Qin Empire.
Some people argue that the form of the banliang coin is symbolic. People in ancient China believed that the earth was square and heaven was round. So, in issuing these coins, Qin Shi Huangdi was placing himself as a direct link between heaven and earth. Others argue that the shape of the banliang is strictly functional in terms of production technique. Banliang coins were cast in moulds, and needed to be filed down after casting. With their square hole, a whole stack of these coins could be slid onto a square-shaped rod, and all filed down at the same time.
J. Williams (ed.), Money: a history (London, The British Museum Press, 1997)