The korowai, also called the Kolufo, are a people of southeastern Papua

Papua (Indonesian province)

Papua comprises most of the western half of the island of New Guinea and nearby islands. Its capital is Jayapura. It's the largest and easternmost province of Indonesia. The province originally covered the entire western half of New Guinea...

 (i.e., the southeastern part of the western part of New Guinea

New Guinea

New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...

). They number about 3,000. Until 1970, they were unaware of the existence of any people besides themselves.
The Korowai language

Korowai language

-References:* The Korowai of Irian Jaya: Their Language in Its Cultural Context by Gerrit J. Van Enk & Lourens de Vries ....

 belongs to the Awyu–Dumut family (southeastern Papua) and is part of the Trans–New Guinea phylum. A grammar and a dictionary have been produced by a Dutch missionary linguist.
The majority of the Korowai clans live in tree house

Tree house

Tree houses, treehouses, or tree forts, are platforms or buildings constructed around, next to or among the trunk or branches of one or more mature trees while above ground level...

s on their isolated territory.