Treaty of Nerchinsk
The Argun or Ergune (, , "Ergene gol"; , "Ergüne mörön"; "Yergenye", "Éěrgǔnà hé") is a long river that forms part of the eastern China–Russia border, together with the Amur (Heilong Jiang). Its upper reaches are known as Hailar River () in China. The Argun marks the border (established by the Treaty of Nerchinsk in 1689) between Russia and China for about , until it meets the Amur.