Such powers as Kyushu tandai (the Military Governor of Kyushu), shugo (provincial governor appointed by the shogun), and kokujin (native chieftains, certain local powers) were authorized to have traffic for both diplomatic and commercial purposes, and the ships which brought those envoys were called Shisosen (envoy sending ship).
九州探題や守護・国人のような大勢力に対しては外交と公貿易を兼ねた通交が許可され、それら通交使節を派遣する船は使送船と呼ばれた。