蔡溫
At the age of 27, Sai On traveled to Guangzhou in China, where he studied economics, geography, and political administration alongside the more traditional Chinese classics. Upon returning from China, Sai On was made instructor to the Crown Prince; upon the prince's accession to the throne as King Shō Kei in 1713, Sai On was elevated in position and power, and led the investiture mission to China in 1716. In 1728, he became a member of the "Sanshikan", the Council of Three chief royal advisors. Though Sai On was not of royal blood and so could not be named "Sessei" (a post which historian George Kerr translates as "prime minister"), reorganizations were undertaken within the government allowing Sai On extensive authority and powers. Under his guidance, a number of land reforms were put into place, including the reclamation of land for agriculture, relocation and establishment of settlements, irrigation, flood control, and the planting of trees. In a series of reforms very similar to those implemented in Japan around the same time, strict limitations were placed on farmers moving to the cities, and on the amount of craft work, such as woodworking and metalworking, which farmers were permitted to do. Thus, agricultural production was intensified and made more efficient while artisans were focused in the twin cities of Naha and Shuri. Within a few years of the beginning of the implementation of Sai On's economic reforms and construction, reclamation and conservation projects, the kingdom was producing more than ever before.