During the Yuan-Ming period，a great number of cowrie shells were stored in the Jiangnan treasuries and both the Yuan and the Ming state ordered to move these shells to frontier Yunnan where cowrie shells were used as money. The paper hence explores Chinese，Ryukyu and Japanese sources concerning the origin and transportations of these shells，and argues that while the Maldives islands remained the primary source，the Ryukyu kingdom played a key role in purchasing cowrie shells from Southeast Asia and presenting to Ming China in its tributary missions.