Okinawa has long been contested territory. Fonnerly an independent kingdom known since the thirteenth century as the Ryukyu Okoku (Ryukyu Kingdom), its nationhood status was totally compromised in 1609 when the Satsuma daimyo (feudal lord) of southern Japan invaded the nation. The aim of the daimyo was to secure trading rights for his own southern Japanese fiefdom in an era of encroaching national coherence and isolationism in Japan proper. Although in reality controlled by representatives of Satsuma, the Ryiikyii King fonnally ruled until 1879, and in keeping with the mandate of Satsuma's demands and Ryukyu's traditions, the Ryukyu Kingdom retained its trading, religious, and cultural ties with China. Following Japan's modernization in the late nineteenth century, the Satsuma arrangement was rendered moot when the Meiji state fonnally annexed the Ryukyus and renamed the island chain Okinawa Prefecture. A governor was appointed to administer the islands; Japanese was introduced as the lingua franca; Japanese education, military, and agricultural practices were imposed; and Okinawans were encouraged to improve their sugar cane production through low-cost government loans.