Ancient Chinese coinage includes some of the earliest known coins. These coins, used as early as the Spring and Autumn period (770–476 BCE), took the form of imitations of the cowrie shells that were used in ceremonial exchanges. The Spring and Autumn period also saw the introduction of the first metal coins; however, they were not initially round, instead being either knife shaped or spade shaped. Round metal coins with a round, and then later square hole in the center were first introduced around 350 BCE. The beginning of the Qin Dynasty (221–206 BCE), the first dynasty to unify China, saw the introduction of a standardised coinage for the whole Empire. Subsequent dynasties produced variations on these round coins throughout the imperial period. At first, distribution of the coinage was limited to use around the capital city district but by the beginning of the Han Dynasty, coins were widely used for such as when paying tax, salaries and fines.
Ancient Chinese coins are markedly different from coins produced in the west. Chinese coins were manufactured by being cast in molds, whereas western coins were typically cut and hammered or, in later times, milled. Chinese coins were usually made from mixtures of metals such copper, tin and lead, from bronze, brass or iron: precious metals like gold and silver were uncommonly used. The ratios and purity of the coin metals varied considerably. Most Chinese coins were produced with a square hole in the middle. This was used to allow collections of coins to be threaded on a square rod so that the rough edges could be filed smooth, and then threaded on strings for ease of handling.
Official coin production was not always centralised, but could be spread over many mint locations throughout the country. Aside from officially produced coins, private coining was common during many stages of history. Various steps were taken over time to try to combat the private coining and limit its effects and making it illegal. At other times private coining was tolerated. The coins varied in value throughout the history.