The Okinawan islands were unified by the Ryukyu Kingdom in the 12th century. She paid tribute to the Ming Dynasty and then the Qing Dynasty. In the early 17th century the kingdom was conquered by the Satsuma Han of Kyushu. Satsuma kept the kingdom nominally alive because of benefit from trade with China. During the Meiji peroid, the kingdom was formally abolished and the Okinawa prefecture was established. After World War II Okinawa was trusted by the U.S. In 1972 Okinawa returned to Japan. Although in early modern times the Okinawans experienced national awakening, Okinawa became more an more integrated into the society of the Japanese mainland.