Most TNG languages are spoken by only a few thousand people, with only four (Melpa, Enga, Western Dani, and Ekari) being spoken by more than 100,000.
The greatest linguistic diversity in Ross's Trans-New Guinea proposal, and therefore perhaps the location of the proto-Trans-New Guinea homeland, is in the interior highlands of Papua New Guinea, in the central-to-eastern New Guinea cordillera where Wurm first posited his East New Guinea Highlands family.