The Ryukyu Kingdom was an island state centered on Okinawa, conventionally dated from the 1429 unification under Shō Hashi to its annexation by Japan, which Japan staged as the Ryukyu Domain in 1872 and completed as Okinawa Prefecture in 1879. It grew rich as a trading go-between linking Ming China with Japan, Korea, and Southeast Asia, and it developed its own languages, court culture, and religion. After Satsuma's 1609 invasion it remained formally distinct but constrained under Japanese authority, while maintaining tributary diplomacy with China.
In 1458 the king of a small island realm hung a bronze bell in his throne hall at Shuri. Its inscription announced that his kingdom sat between China, Japan, and Korea, gathered the goods of ten thousand countries, and served as a bridge among all nations. The boast was not empty, and it was not backed by anything usual. Ryukyu had no gold, no great grain surplus, no standing army, and a modest population scattered along a thin chain of islands. What it had was a position on the sea lanes and a trading privilege at Chinese ports that almost no one else could get. Five centuries later the bell was blackened by American shellfire but survived the destruction of that same castle, on an island that had become the bloodiest battlefield of the Pacific war.