Coin history - 
 The 5 Dynasties and Ten Kingdoms A.D. 907

The 53 years that followed the fall of the Tang were a period of disunity and chaos. As the histories only mention some of the coins that were minted, and most of the information we have has come from archaeological excavations. In this short period many types of coins were cast, and many were very large coins. The highest denomination was 10.000, which had never been seen before. 
Some of the coins of this period were only cast for a very short period, and only a few pieces are known to exist today. A few types of iron coins had been cast earlier on in the Han, the Three Kingdoms and the Northern and Southern dynasties, but now many small and large coins were cast in both lead and iron. 

Yang Lien-sheng writes (p. 28) that lead coins were cast in Fujian in 916 A.D., and shortly after coins were also cast in iron. The neighboring states followed this practice. Iron and lead were circulated in the cities and bronze in the countryside. This was a good way to balance imports and exports because foreign tradesmen could not use the iron and lead coins they received as payment in other states, and had to use it before they left. Peng mentions very little about why iron and lead were used for coins: he merely writes that the King of the Chu was advised to use iron and lead because it was available in large amounts (p. 263).

It was, according to Peng (p. 313), during the Tang that the modern word huobi began to have its modern meaning of money. Huo and bi both meant commodities, but had previously also been used as words for money. In the Tang huo and bi together began to appear as a noun that referred to money. Peng points out that this clearly illustrates how money evolved out of commodities.