Wu Zhu

Wu Zhu (Chinese: 五銖) is a type of Chinese cash coin produced from the Han dynasty in 118 BC when they replaced the earlier San Zhu (三銖; "Three Zhu") cash coins, which had replaced the Ban Liang (半兩) cash coins a year prior,^[1] until they themselves were replaced by the Kaiyuan Tongbao (開元通寳) cash coins of the Tang dynasty in 621 AD. The name Wu Zhu literally means "five zhu" which is a measuring unit officially weighing about 4 grams however in reality the weights and sizes of Wu Zhu cash coins varied over the years. During the Han dynasty a very large quantity of Wu Zhu coins were cast but their production continued under subsequent dynasties until the Sui.^[2]

The production of Wu Zhu cash coins was briefly suspended by Wang Mang during the Xin dynasty but after the reestablishment of the Han dynasty, the production of Wu Zhu cash coins resumed, and continued to be manufactured long after the fall of the Eastern Han dynasty for another 500 years.^[3] Minting was definitively ended in 618 with the establishment of the Tang dynasty. Wu Zhu cash coins were cast from 118 BC to 618 AD having a span of 736 years, which is the longest for any coin in human history.^[4]