The Baliem Valley is a valley of the highlands in Western New Guinea, Indonesia occupied by the Dani people. 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, with a population of over 200,000.
As far as the outside world was concerned, the discovery of the Baliem Valley 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 found what the expedition called the "Grand Valley". Since then the valley has gradually been opened up to a limited amount of tourism, with Baliem Valley Festival as a main tourist event.
The following is copied from the back cover of Peter Matthiessen’s book Under the Mountain Wall:
In the Baliem Valley in Central New Guinea live the Kurelu, a Stone Age tribe that survived into the twentieth century.