Furthermore, Kaikin Policy (the policy to forbid private people to trade with foreign countries) and the establishment of a currency system based on silver and coins (excluding copper coins) by the Ming Dynasty reduced the necessity of minting copper coins, naturally decreasing the amount of copper coins that were brought into Japan as well.
更に明の海禁政策や銀と貨幣による通貨体系の確立（銅銭の除外）は銅銭鋳造の必要性を減らし、当然日本への流入も減少した。