In the book Sangoku Tsuran Zusetsu (Illustrated Outline of the Three Countries) written by Japanese scholar Hayashi Shihei in 1785, the attached map of the three provinces and 36 islands of Ryukyu also marked the Diaoyu Islands as being outside the scope of the Ryukyu Islands and with the same color as the Chinese mainland.
The Chuzan Seikan (Mirror of Chuzan), compiled by the Regent of the Ryukyu Kingdom in 1605, identified Kume (present-day Kumejima Island, east of Chiwei Islet) as the boundary of the Ryukyu Kingdom. The maps and references in the Chuzan Seifu (Genealogy and Annals of Chuzan), presented in 1701 by an envoy dispatched by the Ryukyu Kingdom as a tribute to the Qing Emperor, recorded the 36 islands of the Ryukyu Kingdom, and the Diaoyu Island and its adjacent islets were not part of them. In the late 1870s and early 1880s, the Qing Dynasty’s chief diplomat Li Hongzhang and his Japanese counterparts confirmed during the negotiations on the sovereignty over the Ryukyu Islands that the Ryukyu Islands consisted of the 36 islands, and the Diaoyu Islands were not part of them. The relevant 19th century documents and maps from Western powers such as Britain, France, the United States and Spain also acknowledged that the Diaoyu Islands belonged to China. A Map on China's East Coast from Hong Kong to the Liaodong Bay, compiled by the British Navy in 1877, identified the Diaoyu Islands as being affiliated to China’s Taiwan and distinctly separated them from Japan's Nansei Islands, or the Ryukyu Islands. This map was later on widely referred to in international exchanges and was used to demarcate the Penghu Islands during the negotiations of the Treaty of Shimonoseki.
In 1941, the so-called "Taihoku (Taipei) Prefecture", which was then under the Japanese occupation, came into duspute with Okinawa Prefecture over the fishing grounds on the Diaoyu Islands. In handling this case, the Japanese court ruled that the Diaoyu Islands should be under the jurisdiction of "Taihoku Prefecture". Ryozo Fukuda, who served as the head of the "Taiwan Police Department" during the Japanese occupation of Taiwan, confirmed that the Diaoyu Islands were, at the time, under the jurisdiction of the "Taiwan Police Department", and licences were issued by “Taihoku Prefecture” to Taiwanese fishermen to operate around the Diaoyu Islands. All these facts prove that even under Japan's colonial rule, these islands were administered as Taiwan's affiliated islands.
In December 1943, the heads of China, the US and the UK issued the Cairo Declaration in which it was stated that all the territories Japan had stolen from the Chinese should be restored to China. In 1945, it was reiterated in the Potsdam Proclamation that "the terms of the Cairo Declaration shall be carried out and Japanese sovereignty shall be limited to the islands of Honshu, Hokkaido, Kyushu, Shikoku and such minor islands as we determine". In August that year, Japan accepted the Potsdam Proclamation and surrendered unconditionally. In accordance with the Cairo Declaration and the Potsdam Proclamation, China recovered the territories stolen by Japan such as Taiwan and the Penghu Islands. According to international law, the Diaoyu Islands, which are Taiwan's affiliated islands, have been simultaneously returned to China.
4. Japan's illegal occupation of the Diaoyu Islands
Tatsushiro Koga, a Japanese national, explored the Diaoyu Islands in 1884 and claimed that he found the islands to be terra nullius. From 1885 to 1893, the Okinawa Prefecture requested permission thrice from the Japanese government to place the Diaoyu Islands under its jurisdiction and put up boundary markers. The Japanese government rejected the requests fearing reprisals from the Qing government. In January 1895, as the Qing Dynasty’s defeat in the First Sino-Japanese War was all but certain, the Japanese government illegally occupied the Diaoyu Islands and "incorporated" them into Okinawa Prefecture. In April the same year, by signing the unequal Treaty of Shimorioseki, Japan forced the Qing Dynasty to cede "the island of Formosa (Taiwan), together with all islands appertaining or belonging to the said island of Formosa" to Japan. In 1900, the Japanese government renamed the Diaoyu Islands the "Senkaku Islands".
5. Backroom deals between Japan and the United States and protest statements by China
The Treaty of Peace with Japan (commonly known as the Treaty of San Francisco) was signed by Japan, the United States and other countries on 8 September 1951, agreeing to place the southwestern islands south of the 29th parallel of north latitude under its trusteeship system, with the United States as the sole administering authority. In December 1953, the Ryukyu government under the United States trusteeship issued a proclamation defining its geographical boundary lines, with the Diaoyu Islands being clearly included.
On 18 September 1951, Zhou Enlai, then Chinese Premier and Foreign Minister, made a solemn statement on behalf of the Chinese government that the Treaty of Peace with Japan signed in San Francisco was illega1 and invalid and could under no circumstances be recognized by the central government of China as China was excluded from its preparation, formulation and signing.
On 17 June 1971, Japan and the United States signed the Okinawa Reversion Agreement, which provided that all and any powers of administration over the Ryukyu Islands would be returned to Japan on 15 May 1972. The agreement included the Diaoyu Island and its adjacent islets in the territories and territorial waters to be reversed to Japan. On the same day the agreement was signed, the spokesman of the U.S. State Department stated that the