The Baliem Valley (Indonesian: Lembah Baliem; also spelled Balim and sometimes known as the Grand Valley) is a valley of the Central Highlands in Western New Guinea, specifically in the province of Highland Papua, Indonesia. The main town in the valley is Wamena, which lies on the Baliem River. The valley is about 80 km in length by 20 km in width and lies at an altitude of about 1,600–1,700 metres (5,200–5,600 ft), with a population of over 200,000.
The discovery of the Baliem Valley to the Western world and the unexpected presence of its large agricultural population was made by Richard Archbold’s third zoological expedition to New Guinea in 1938. On 21 June an aerial reconnaissance flight southwards from Hollandia (now Jayapura) found what the expedition called the "Grand Valley". Flights in later weeks described fenced villages of 3-50 houses, farm fields and drainage ditches. They landed on Lake Habbema 15 miles west. Teams of Dutch soldiers and Dayak people recruited from Borneo collected flora and fauna in the Baliem Valley, but did not know the language and killed one native without firing a warning shot. 10-15 villages formed a neighborhood, within an hour's walk. Several neighborhoods made a confederation, and several confederations made an alliance of 4,000-5,000 people, which was constantly fighting feuds to avenge previous deaths caused by members of other alliances, though all had the same culture, ethnicity and language.