According to Chen Chieh-hsien, a specialist in Qing dynasty history, there were annual trips back and forth between Ryukyu and China in connection with the tributary relationship, and in some years there was more than one. The nominal purpose of the missions varied. Ships were dispatched on trips to deliver tribute, receive tribute, escort tribute missions, receive emissaries, etc.
清代史專家陳捷先指出，當時琉球的貢船、接貢船、海難船、護送船、迎使船、謝恩船，以及以其他名目派出來華的船隻，可說每年都有，甚至還有一年好幾起的。