Coin was issued by emperor Wu Ti (Who ruled from 502-549AD) in the name of his reign title Pu Tung - which he took on in 520AD. We believe that this coin was issued exactly in 523AD because coin historian Schjoth in his early 20th century book (Page 17) says:

"The Book of Liang states that in the 4th year of P'u-t'ung (AD 523) the Emperor Wu caused the casting of iron coins."

These iron coins were issued with the same value as copper coins. The problem with that was that iron was massively cheaper than copper and as such this would have been a fiduciary coin. This means that somebody had to guarantee its value because the coins were worth more than the metal content that it contained (Sort of like modern day paper money). As a result it was profitable to run a counterfeiting operation making iron coins. All throughout Chinese history counterfeiting coins was a big problem because it was easy to do and weight standards were usually dodgy and inconsistent at best. But counterfeiting was particularly bad during emperor Wu's time because over the previous 20 years he was often trying to overvalue coins (Even issuing 100 and 1000 cash coins). So a larger than normal counterfeiting industry sprang up during this period. Counterfeiters were even going so far as to make coins that looked like they were chipped around the edges to make it look like a genuine coin that somebody clipped to steal some of the copper around the edges to make more coins. As a result this experiment with making Iron coins didn't last long.

The rarity of these iron coins is much greater than the cost would indicate given comparisons with many other Chinese coins. Getting them in decent shape is also difficult given the wearing patterns of Iron and the limited number that were issued.