During the 16th to 18th century, the world exchanged with each other through the ocean, and sweet potatoes were transferred to the oriental society in the process that the western powers advanced to the east. The point where sweet potatoes first were transferred was Nanao-island(南澳島), China in 1584. Afterwards, Ryukyue, Japan in 1597, Tsushima in 1715, and Joseon in 1763. The characteristic that appeared in the process of transferring sweet potatoes to the orient three countries was moving slowly by using Island area as stepping-stones, which were continued one by one in the Southeast Asia, and all of those who took the key role of transferring sweet potatoes were maritime powers. Therefore, by investigating the inflow process of sweet potatoes, each of East Asian nation's awareness on ocean and marine policy of that time could be comprehended.
China was positioned as the most profitable position in sweet potatoes inflow, in geographical, economic, and political aspects, however due to the continuous the ban on maritime trade policy(海禁政策) during the Ming·Qing dynasty, Fujian Province(福建省)’s sweet potatoes could not be transferred to Zhejiang Province(浙江省)’s Joushan-island(舟山島), rather it resulted in reimportation from Japan. This is not mere a characteristic that appeared in the inflow of sweet potatoes, but it can be said to be a symbolic event that the ban on maritime trade policy acted as an obstacle in accepting advanced civilization. In case of Joseon, the nation enforced stronger the ban on maritime trade policy than Ming·Qing dynasty in the frame of tribute installation system, and became the most unknown hermit nation in the world, by implementing only limited exchange with China by land. Eventually, the sweet potatoes which could have arrived in five days during Koryo Dynasty, took 179 years to arrive in the mid and late Joseon Dynasty. In case of Japan, it implemented an open maritime polity with the spirit to learn from barbarians, excluding Hua Yi spirit(華夷精神), so that advanced civilization e.g. sweet potatoes, etc. could arrive earlier.
Finally, each nation’s awareness on ocean resulted in the difference in the view of the acceptance of important crops as sweet potatoes, i.e. advanced civilization, which eventually divided destiny of each nation.