The late 16th and early 17th centuries witnessed a significant change in the geopolitical structure of East Asia. The power of the Ming dynasty was declining due to internal and external troubles and depleted finances, whereas Japan had been rising steadily since Toyotomi Hideyoshi unified the country. The traditional East Asian international order, centered on the Ming dynasty and based on the tributary system, faced a challenge from Japan. Against this background, the invasion of the Ryukyu Kingdom by the Japanese feudal domain of Satsuma had a great effect on the existing regional geopolitical structure. With the establishment of the ＂dual subordination＂ of the Ryukyu Kingdom, a new geopolitical structure gradually took shape in which the two great powers, China and Japan, competed for dominance. The Ming dynasty＇s limited awareness of maritime issues and of the geostrategic importance of the Ryukyu Islands, its passive attitude towards Satsuma＇s invasion, and especially, its tolerance of the Ryukyu Kingdom＇s ＂dual subordination＂ fed Japan＇s ambitions for further expahsion and encouraged its ultimate annexation of the kingdom by force. It can be said that the military conquest of the Ryukyu Kingdom by Satsuma foreshadowed the decline of the Ming and the rise of Japan.
