The Amami Islands were a focal point for dispute between the southward-expanding Satsuma Domain and the northward-expanding Ryukyu Kingdom. In 1453, a group of Koreans were shipwrecked on Gaja Island, where they found the island half under the control of Satsuma and half under the control of Ryukyu. Gaja Island is only 80 miles from Satsuma's capital at Kagoshima City. The Koreans noted that the Ryukyuans used guns "as advanced as in [Korea]". Other records of activity in the Amami Islands show Shō Toku's conquest of Kikai Island in 1466, a failed Satsuma invasion of Amami Ōshima in 1493, and two rebellions on Amami Ōshima during the 16th century. The islands were finally conquered by Satsuma during the 1609 Invasion of Ryukyu. The Tokugawa shogunate granted Satsuma the islands in 1624. During the Edo Period, Ryukyuans referred to Satsuma's ships as "Tokara ships".