In addition, with an aim to prevent piratical private trades by wako (Japanese pirates), the dynasty came to desire peaceful trades with Japan (trade between Japan and Yuan Dynasty) by establishing Shihakushi (the public office that operated on trade on the sea in China from T'ang-Dynasty period to the Ming Dynasty period) in Quanzhou, Qingyuan, and Ningbo.
また当時出没し始めた倭寇による海賊的私貿易を防ぐ意味からも、沿岸部の広州・泉州・慶元（寧波）などに市舶司を置き、日本との平和的な交易を望むようになっていた（日元貿易）。