Nearly three-fourths of the population of Bihar is concentrated in the
cultivated plains. The harnessing of the Kosi River has stabilized
settlement in its valley. On the South Bihar Plain, a highly developed
system of irrigation supports a large population. Density declines
toward the south. Settlement in Chota Nagpur is confined largely
to river valleys, deforested peneplains (areas reduced almost to plains
by erosion), and mineral and industrial belts.
The great majority of the people live in villages. Compact or clustered
villages are usually found in the plains, while dispersed rural
settlements are characteristic of the plateau. Aboriginal tribes are
concentrated in Chota Nagpur, especially in the districts of
Ranchi, Singhbhum, and Santhal Pargana. Santhal, Oraon, Munda, and Ho
are the principal tribes and together constitute four-fifths of the
total tribal population.
. Christianity and animism are largely confined to Chota
Nagpur. Of the tribal population (outside the
caste hierarchy), most are Hindus, a few are Christians, and many adhere
to animism. The Ho is the only tribe in which the majority follow
animism; Kharia is the only tribe in which the majority are
Christians. Christianity is significant among the Mundas and Oraons.
Austro-Asiatic (Mundari, Santhali, Ho) and Dravidian (Oraon)
languages are confined to the aboriginal tribes.