Asian trade (15th-16th century)
Diplomatically, the kingdom established tributary relations with China during its Ming and Qing Dynasties. It also developed trade relations with Japan, Korea and many Southeast Asian countries, including Siam, Pattani, Malacca, Champa, Annam, and Java.
 

Between the 15th and 16th centuries, the Ryukyu Kingdom emerged as the main trading intermediary in Eastern Asia. Japanese products—silver, swords, fans, lacquer-ware, folding screens—and Chinese products—medicinal herbs, minted coins, glazed ceramics, brocades, textiles—were traded within the kingdom for Southeast Asian sappanwood, rhino horn, tin, sugar, iron, ambergris, Indian ivory and Arabian frankincense. Altogether, 150 voyages between the kingdom and Southeast Asia on Ryukyuan ships were recorded, with 61 of them bound for Siam, 10 for Malacca, 10 for Pattani and 8 for Java, among others.

Commercial activities in the kingdom diminished around 1570 with the rise of Chinese merchants and the intervention of Portuguese and Spanish ships, corresponding with the start of the Red Seal Ship system in Japan.

Reference

http://www.experiencefestival.com/ryukyuan_people

http://zh.wikipedia.org/w/index.php?title=%E7%90%89%E7%90%83%E5%9C%8B&variant=zh-tw