evidence: Noktundo is a former island (currently a peninsula) in the delta of the Tumen River on the border between Primorsky Krai, Russia and North Korea. The area of the island was 32 square kilometres (12 sq mi). In the 15th century, Noktundo belonged to the Jurchen. In 1587 there was a battle fought on this island between the local Jurchen and the invading army from Yi Sun-sin, a general of Korea. The island was under Qing control until the 1860 Convention of Peking, the Qing Dynasty ceded the island to the Russian Empire. This became a matter of protest to the Koreans, who claimed that the Qing had no authority to do so. In 1990, the former Soviet Union and North Korea signed a border treaty which made the border run through the centre of the river leaving the territory of the former island on the Russian side. South Korea refused to acknowledge the treaty and demanded that Russia return the territory to Korea.