(rēō'kyō), Jap. Ryukyu-retto or Nansei-shoto [southwest group], archipelago (1990 est. pop. 1,500,000), c.1,850 sq mi (4,790 sq km), SW Japan, in the W Pacific Ocean. The chain stretches about 650 mi (1,050 km) between Taiwan and Japan, separating the East China Sea from the Philippine Sea. The Ryukyus are composed of three principal groups: they are, from north to south, the Amami Islands (part of Kagoshima prefecture), the Okinawa Islands, and the Sakishima Islands (both part of Okinawa prefecture). Okinawa is the largest and most important island of the Ryukyus. The islands are the exposed tops of submarine mountains and are of volcanic or coral origin; there are several active volcanoes in the group. Although the islands are low, with few points above 2,000 ft (610 m), they have rugged hills and little flatland. The Ryukyus have a subtropical climate with much rain and are often hit by typhoons. The chief agricultural products are sugarcane, sweet potatoes, pineapples, and rice. …