To address the Sino-Japanese dispute of Diaoyu Islands (referred to as Ryukyu Islands by the Japanese), it is necessary to study the history of Ryukyu. In this book, the author collects abundant documents and makes some breakthrough on the unsettled history of Diaoyu Islands. In recent years, Japan has argued that Diaoyu Islands is an outlying island of Okinawa Prefecture, thus should belong to Japan. This book demonstrates that Diaoyu Islands never belongs to Okinawa, supported by suffcient historical facts, effectively refuting the absurdity of Japan’s argument. This book was written in the historical order from Sui Dynasty (581-618) with the earliest records on Ryukyu to the end of the World War II when Ryukyu was eventually included into Japan. Having studied Sino-Japanese relations for many years, the author notes down how Ming and Qing Dynasties of China protected and helped Ryukyu, and how Ryukyu paid tributes to China for fve centuries.