The first written material which recorded Diaoyu Island in Japan was seen in 1785 in a book titled Illustration on Three Countries by Hayashi Shihei, which contains a map showing three prefectures and 36 islands in Ryukyu. The book, however, was also based on the book by Chinese envoy Xu Baoguang. The map marks the chain with its Chinese name "Diaoyutai" and paints the islands in light red like China's Fujian and Zhejiang provinces; meanwhile, it marks the Kume Island in brown color like Ryukyu. The book also quotes Xu's words, saying that Kume Island is "the mountain serving to guard the southwest border of Ryukyu".
Another book, Annals of Southern Islands, written by Japanese scholar Arai Kimi in 1719, also mentions 36 islands under the jurisdiction of the Ryukyu Kingdom, which do not include Diaoyu Islands. A map published in 1875 showing Japanese prefectures doesn't mark Diaoyu Islands yet. Even in 1879, when the Qing Minister Li Hongzhang negotiated with Japan on the ownership of the Ryukyus, both sides confirmed that they were composed of 36 islands, and did not include the Diaoyu Island Chain.
In addition, the most authoritative history-recording book of the Ryukyu government, written by Kozoken in 1650, recognized the statement of Chinese envoy Chen Kan of the Ming Dynasty that the Kume Island belonged to Ryukyu, but Chiyu Islet and the islands to its west did not. Kozoken was Ryukyu's prime minister and the most authoritative scholar, and his point of view undoubtedly represented the position of the rulers of Ryukyu at that time.
Thereafter the Ryukyuan scholar Teizhunsoku described Kume Island as the mountain guarding the southwest border of Ryukyu in his Guidebook in 1708. Another scholar Saion wrote the Revised Pedigree of Zhongshan and other works in 1726 and pointed out that the Ryukyu territory excluded Diaoyu Islands. Furthermore, the atlas in the Pedigree of Zhongshan that Ryukyu presented to Chinese Emperor Kangxi of the Qing Dynasty also did not cover Diaoyu Islands.
Shogoro Takahashi, former director of the Japan Association for the Promotion of International Trade, concluded from his research that the names of the islets in the Diaoyu Island Chain are of Chinese origin. Huangweiyu (Huangwei Island) and Chiweiyu (Chiwei Island) are obviously Chinese names because they are similar to Huapingyu, Mianhuayu, and Pengjiayu, islands affiliated with Taiwan Island. Japan has no islands with names ending in "yu". In Fujian Province, Penghu Islands and Taiwan Province, however, there are 29 such islands. Moreover, such names can be easily found in ancient Chinese maps. Chiweiyu was mentioned as Chiyu in ancient Chinese books, and took its name from the color of the aqueous rock from which it was formed.
In an attempt to justify Japan's territorial claim to the Diaoyu Island Chain, some Japanese argued that even some Chinese-published maps use the Japanese name of Senkakus for the islets or simply fail to identify them at all. According to Qing Dynasty maps, Diaoyu Islands were named as Diaoyutai, which is still used by Taiwan. In the Chinese maps published during the period of Japanese occupation, like the New Map of China published by Shanghai's Shengpao newspaper, the islands were renamed as the Senkakus, or left unmarked under Japanese pressure. This has either been followed by or exerted an influence on some publishers of maps appearing after 1945 and even those published after the founding of the People's Republic of China in 1949. For instance, in its first edition in 1956 and the second edition in 1962, the Map Album of Chinese Provinces noted at the end that the maps were based on those published by Shengpao either during the War of Resistance Against Japan or prior to 1949. These facts suggest that the omissions or mistakes are a result of Japanese aggression and occupation of China. This, however, is just a scar left by colonialism imposed on China, and can in no way provide justification for Japan's territorial claims.
In fact, official Japanese maps and documents once officially used the Chinese names for the islands. Incomplete statistics reveal that two-thirds of the 21 types of Japanese maps and encyclopedias published between 1935 and 1970 did not record the so-called Senkaku Islands, and some of them used the designation of Uotsuri-jima. The naming of the adjacent islands of the Diaoyu Chain is even more chaotic. It is said that the word Senkaku was in fact borrowed from Sento, a British term for the islands, by Iwatsune Kuroda, a teacher from the Okinawa Normal College in May 1900. It was not until July 25, 1921, when the Japanese government included the islands as "imperial territory" into the Japanese maps, did Japan rename Chiweiyu as Taishoto, although it was not officially used over a long period of time.