Kōsō Tsūhō (Huangsong Tongbao)

First cast in the second year of Baoyuan of the Northern Song, it is among the most numerous of the coins excavated in Japan. To an island where the court had stopped casting coin after the Kengen Taihō, the ships of the Song merchants living in Hakata brought this in during the twelfth century. Not an imperial edict but the profit and loss of the merchants gathered at Hakata was what remade this country's money.