China is stirring up a new clash with Japan over something that’s been settled for more than 400 years:  Possession of Okinawa and the Ryuku Islands.

The People's Daily, the Chinese Communist Party's mouthpiece, published a commentary by two Beijing-backed scholars who questioned Japan’s ownership of the Ryuku islands and suggested the islands had earlier belonged to China.

In fact, Okinawa has been part of Japan since 1609. Prior to that, Okinawan Kings had paid tribute to various Chinese courts to avoid invasion.

Japan's Chief Cabinet Secretary Yoshihide Suga made it clear the islands are Japanese territory.

“Japan lodged a stern protest that we can by no means accept the article in question if it reflects the Chinese government's stance,” Suga said.  China responded by claiming that scholars wrote the piece as individuals.

Okinawa is host to about 50 Thousand US military personnel in Japan and is the largest island in the Ryukyu chain.

The latest angry exchange further clouds tense relations between Asia's two-largest economies when they’re already in a stand-off over the Senkaku Islands.