The National Library of China on Monday presented historical documents, atlases and ancient journals regarding the Diaoyu Islands and their affiliated islets in the East China Sea.

The documents are intended to demonstrate that China discovered the Diaoyu Islands at the beginning of the 15th century, as well as put them under its jurisdiction as affiliated islets of Taiwan.

The central government folded the Diaoyu Islands into the defense scope of east China's Fujian province, the documents show.

In 1885, the Meiji administration of Japan found the islands through an investigation by Okinawa authorities in 1895.

It is "a sheer historical lie" for Japan to claim sovereignty over the Diaoyu Islands based on the principle of "first come, first served," according to a statement from the library.

The "Record of the Imperial Envoy's Visit to Ryukyu" displayed at the exhibition represents the earliest Chinese document to record the maritime boundaries of China.

It says that in 1372, Emperor Zhu Yuanzhang of the Ming Dynasty (1368-1644) dispatched the first envoy to Ryukyu, an area that acted as a Chinese vassal state during the following Qing Dynasty (1644-1912) until Japan annexed Ryukyu and renamed it Okinawa at the end of the Qing Dynasty, said librarian Huang Runhua.

China sent envoys to Ryukyu 24 times during both dynasties, as noted in the record, Huang said.

"Ryukyu's people believed that they reached their country by way of the Diaoyu Islands," he said, noting this shows the Diaoyu islands are part of China's territory without any doubt.

The exhibition also featured an atlas compiled by General Hu Zongxian and geographer Zheng Ruozeng that marked the Diaoyu Islands as part of China's coastal defenses in 1562, marking the earliest record of China's formal jurisdiction over the islands.

Other defense atlases were also presented at the exhibition, as well as books written by Japanese academic and historian Kiyoshi Inoue that state the islands belong to China.

The exhibition also featured historical editions of the People's Daily, the flagship newspaper of the Communist Party of China (CPC), containing declarations and statements by the Foreign Affairs Ministry regarding the Diaoyu Islands.

After the Japanese government announced its plan to "purchase" the Diaoyu Islands earlier this month, the Chinese government has issued statements expressing its firm opposition to Japan's move.

Protests against the purchase have been seen across China over the past few days.

To affirm its sovereignty, China has sent surveillance ships to patrol waters around the Diaoyu Islands, as well as released geographic coordinates, base points and baselines for the islands.