China claims to have controlled the area where the islands sit since the Ming dynasty about 600 years ago, but Japan unveiled a report calling that claim into question.
The Tokyo 'paper Yomiuri Shimbun cites a 17th century document from a Chinese official sent to a Japanese envoy explaining the dynasty's control ended far short of the Senkaku Islands.
From the Yomiuri:
During China's Ming dynasty, a provincial governor told a Japanese envoy that the ocean area under the dynasty's control ended with the Matsu Islands, now under Taiwan's administration, and the sea beyond that was free for any nation to navigate, said Nozomu Ishii, an associate professor of Nagasaki Junshin Catholic University.
The Matsu Islands are much closer to China than the Senkaku Islands, which China claims to have controlled since the Ming dynasty about 600 years ago. At a press conference Monday, Ishii said the Chinese governor's statement appears in "Huangming Shilu", the official annals of the Ming dynasty.
"This historical material proves that Japan's claim over Senkaku Islands is historically correct," he said.
The islands called Senkaku in Japan and Diayo in China are the focus of many recent verbal exchanges and confrontations between the Japanese and Chinese military.