Chinese coins cast in brass with a square hole in the middle have an extremely long history, and played a pivotal role in the rise and development of Chinese commerce and culture.  During the time of the early construction of the Great Wall of China and the reign of the first Emperor of China around 220 BCE, Chinese coinage was standardized to allow for easy commerce and trade through the vast new empire.

Further standardization was introduced in 621 CE with the creation of the “cash” currency denomination (Chinese: 文; pinyin: wén).  Production of this style of coin would continue for more than 2200 years until after the end of the Chinese empire in 1911. 

Coins of the Northern Song Dynasty (960 to 1127CE) were produced during a time of relative stability in China, with significant economic and cultural growth.  With an ample supply of hard currency, trade flourished and there was a wide exchange of ideas and technology.  One of the most important developments during this time was the introduction of wood block printing, allowing ideas to be shared widely across the empire. 

With just one relatively low value denomination forming the main basis of commerce, making large purchases could prove challenging.  However, a simple solution was found to solve this problem.  Using the hole in the center of the coins, standard quantities of 100, 500 or 1000 coins could be strung together to form new larger trading units.  In this way, large purchases could be completed even without using silver or gold coinage.

Methods used to produce large quantities of cash coins were both simple and ingenious, and markedly different from the struck coins produced in other parts of the world.  Chinese cash coins were cast using a frame filled with moist fine sand, often dusted with fine charcoal dust. Rods would first be impressed into the mould in the shape of a tree trunk with multiple branches.  Carefully engraved “mother coins” or “seed coins” would then be impressed into the bottom half of the mould along the main “branches”, completing the shape of the tree. The top of the mould could then be closed tight to impress the second side of the coin.  The seed coins and rods were then removed, and molten metal poured into the mould to fill the impressions.  This produced a connected tree of coins, which were then broken off, filed or smoothed, and then put onto strings ready for circulation.  This method of production accounts for the typical grainy surface of most cash coins.

Chinese cash coins of the Northern Song dynasty use four characters on the front of the coin. These characters represent the name of the dynasty, the name of the emperor, where the coins was produced (mint mark), and the denomination.  

Today, surviving cash coins dating from ancient to modern times provide collectors with a tangible link to the history of China and a unique opportunity to hold money used in long past eras.  They can also be used as talismans to invite luck and wealth into the home.