Investigations of the Birhor were confined to Hazaribagh District in the southern part of the state of Bihar, India. Hazaribagh District is on the northern edge of the Chota Nagpur plateau. The plateau is 540 to 600 meters in height with isolated rocky hills rising sharply from this surface as much as another 270 meters in altitude. At its northern edge, the plateau drops off sharply to the Gangetic Plain. When approached from this plain, the escarpment appears as a range of rugged, densely forested hills. This topography is the major reason for the continued existence of tribal people in the area despite the existence of a center of fairly advanced civilization in northern Bihar for over 2000 years.

To the west are the central mountain ranges of Madhya Pradesh. To the east, toward the coastal plain of Bengal and Orissa, the plateau is dissected by river drainages to give the configuration of successive ranges of low hills rather than a plateau. The study area is shown in Figs. 7 and 8.

Plant and animal populations on the plateau have been greatly changed in the past three centuries due to the agency of man. All areas of forest have been cut over in the past and most areas are recut often enough to give a dense scrub-forest cover.