Cheng-hua: Year 17, Month 12, Day 23
12 Jan 1482
In Yun-nan, the method of using paper money to pay household tax and merchant tax was set down. At this time, the authorities had memorialized that Yun-nan lacked paper money and thus requested that the tax demands be converted into cowrie-shells. The Ministry of Revenue proposed that of every 10 parts of due taxes, three parts be levied as originally proposed (本色) and that the other seven parts be levied in cowries, with one suo of cowries being converted at from one to three guan of paper money. This was approved.
Zhong-yang Yan-jiu yuan Ming Shi-lu, volume 48, page 3829