Huanqian

Huanqian (literally "ring money") are the round bronze coins with a central hole that were cast by several Chinese states during the Warring States period (475–221 BCE). They are the direct ancestors of the round coin with a square hole that became the standard form of Chinese money for more than two thousand years.

Huanqian appeared from around the fourth century BCE, alongside the older spade money and knife money. Their simple, compact shape proved easier to cast, count and carry, and by the end of the period round coins were spreading across most of the Chinese states.

The origins of the round coin are not fully settled. Some scholars link it to the circular ring on the handle of knife money, others to round discs of jade or stone used as ritual objects. What is clear is that by the fourth century BCE several states were casting flat bronze rings for use as money. The earliest examples are generally associated with the states of the central plains, including Wei and the Zhou royal domain, and with Qin in the west.

Early huanqian had a round central hole. Inscriptions on them commonly name the city of issue, and some state a weight or value. Later in the period, the states of Qi and Yan in the east and north-east began casting round coins with a square hole, with inscriptions that often include a term for money.

Qin's round coins evolved into the ban liang, inscribed with two characters meaning "half liang", a weight standard. The square hole later became the norm because coins could be threaded onto a square rod during finishing, so that their rough edges could be filed down together. Strings of coins threaded through the central hole also became a standard way of counting and storing large sums of cash.

Like other Chinese money of the period, huanqian were cast, not struck. Bronze was poured into moulds made of clay, stone or bronze, and many coins were produced in a single casting on a branching tree of channels. After cooling, the coins were broken off and trimmed. This casting technique stayed at the heart of Chinese coin production until modern machine-struck coins were introduced in the late nineteenth century.

Because states and cities cast their own coins, weights and quality varied. Rulers could gain revenue by issuing lighter pieces, a practice related to seigniorage and to later episodes of currency debasement.

Huanqian circulated as a medium of exchange for trade and taxation within and between states. Hoards from the late Warring States period often mix round coins with spades and knives, showing that different forms of money were accepted side by side, sometimes at locally agreed rates. Gold, weighed rather than counted, served for large payments, while bronze coins handled everyday transactions.

When Qin unified China in 221 BCE, it chose its own round, square-holed ban liang as the single bronze currency of the empire and abolished the regional shapes. The Han dynasty kept the round form and in 118 BCE introduced the wu zhu, which set a lasting standard. The Tang dynasty's kaiyuan tongbao of 621 CE and the vast issues of Song dynasty coinage followed the same pattern.

The round coin with a square hole spread from China to Korea, Japan and Vietnam and remained in everyday use in parts of East Asia into the twentieth century. The huanqian of the Warring States period are therefore the starting point for one of the most enduring coin designs in history, and an important part of the story behind the modern Chinese yuan.

• British Museum – Collection online
• American Numismatic Society