 The coins were not widely used as the Yamato government had trouble distributing to isolated villages.Soon the national currency was reverted to rice instead of coins to exchange for goods and services.There was a decline in the usage and circulation of minted coins by the 10th century as Japanese society began to lose faith in the value of the copper coins as the coins began more diminutive in size and the quality was diluted with an increase in lead due to a shortage of copper.