In result, by reason of the coin was not so much currented as a measure of value and a means of payment, they undervalued the monetary economy of Koryo.
The southern Song dynasty did not enforce the monetary policy to prevent the outflow of coin by special maritime trade supervisorates(shibosi, trading-ship-offices). But people used cloth money(布貨) or silver money mainly on the civil trade and it had been continued to middle age of Yi Chosun Dynasty.
And also it related with mass production of coin as Wang an shi(王安石) enforced the New Policy(新法) in Northern Song Dynasty of Shenzong(神宗) period.We can judge from the excavation that after Sookjong period of Koryo had continued the coinage. The Song dynasty grasped the influence of the Song’s coin’s outflow quite early on, enforced several monetary policies and punished the crimes severely.
By overland route, it was flowed out to the Liao and Jin dynasty.