Hailar (hĪˈlärˈ) [key], city (1994 est. pop. 192,400), Inner Mongolian Autonomous Region., China, on the Hailar (Argun) River. It is an agricultural production center on the Chinese Eastern RR. Formerly known as Hulun, Hailar consists of an old and a new city—the old section, founded in 1734 as a fort, is typically Chinese; the new section is a modern, industrial quarter.