[3] 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.

This tied them closer to the central government and also safeguarded to some extent their economic well-being, as they would no longer need to rely solely on inheritance for their relative wealth.

[8] Okinawa's demand for wood outstripped the ability of the forests to renew themselves on their own, naturally, and the combination of deforestation and rainy weather including regular typhoon seasons led to extensive erosion and landslides.

[9] In addition to these essays, Sai On produced a number of other documents, including a handbook for administrative officials in the provinces entitled Yomui-kan, and Ryokōnin Kokoroe (旅行人心得), or "Travelers' Advice", a guide for Okinawans abroad in China to help them in obscuring from the Chinese the relationship between Okinawa and Japan's Satsuma Domain.

[10] A rival government faction rose up against Sai On in 1734, accusing him of being too pro-Chinese, led by a pair of scholar-bureaucrats, Heshikiya Chōbin and Tomoyose Anjō.