After the Formosan trouble another complication arose between Japan and China with regard to the Islands of Loochoo. These had long been a dependency of Japan. In the middle of the twelfth century the Minamoto leader, Tametomo, driven to the province of Izu, made his way thence to Loochoo, and, having quelled a civil war raging in the islands, placed his son Shunten on the throne. Afterward, the Ashikaga shōgun, Yoshinori, gave the islands to the Shimazu family as an adjunct of the Satsuma fief, but from the time of Hideyoshi's Korean expedition, Loochoo having neglected to discharge its duties as a dependency, the Satsuma chief sent a force to the islands in 1609, took the king prisoner and conveyed him to Edo, whence he was soon after restored to his country. Shimazu then sent officials to superintend the affairs of Loochoo, and from that time forth the revenue of the islands was included in the yearly income of the Shimazu family. In 1873 Sho Tai, king of Loochoo, came to Japan and was formally invested with the title of feudal chief of Loochoo, a residence in Tōkyō being assigned to him at the same time. Shortly afterward the name of the year period and the Loochooan calendar were changed for those in use in Japan, and the laws of the empire were declared operative in Loochoo. Finally, in April, 1879, the feudal title of the ex-king of Loochoo was abolished and the islands were turned into the prefecture of Okinawa. The Chinese government thereupon advanced a claim that Loochoo had once been a tributary of the Middle Kingdom, and that it therefore belonged not less to China than to Japan. The weight of evidence was on Japan's side, however, and by the arbitration of General Grant, ex-president of the United States of America, who happened to be on a visit to the East at the time, the question was settled in Japan's favor.