World’s oldest-known coin mint

When did standardized metal coinage come into use? Controversy has surrounded the subject for generations. The earliest coins were thought to have been minted in China, India, and Lydia in Asia Minor. In China, the hollowed-handled “spade coin” has long been thought to be the earliest metal coinage. Spade coins were imitations of metal spades, but were small and too thin for any practical use. The earliest dates for them were assumed to be between 750 and 500 BC, but this chronology depended on circulated or hoarded coins, not from places where they were produced. Much of the dating was based on pottery styles and other indirect sources.

The city of Guanzhuang 12 kilometres south of the Huang-He river in China’s Central Plains was founded in about 800 BC and abandoned after 450 BC. It was a regional centre of the Zheng state, located at a strategic point for both river ports and a crossroads for major trade routes that ran north to south and east to west. A major craft production zone in the city included extensive bronze and ceramic workshops, also jade production. The bronze workshops used more than 2,000 pits for dumping waste generated during production that included bronze-casting materials, unfinished objects and crucibles. More than 6,000 clay moulds made from local silt produced a wide array of tools including bronze weapons and ritual vessels, even musical instruments. Both finished spade coins and their clay moulds abounded, the coins being manufactured with an alloy of over 66 percent copper and lead. Judging from the moulds, Guanzhuang’s spade coins were highly standardized and carefully measured for size. Standardized coin production here has been AMS radiocarbon dated to just after 640 BC to 550 BC. This is currently the earliest securely dated coin production centre in the world.

Image: Aerial view of the foundry in Guanzhuang – this highly organized site was capable of mass-producing the world’s oldest-known metal currency.

Photo: H. Zhao