Among the 68 million citizens of India who are members of tribal groups, the Indian tribal religious concepts, terminologies, and practices are as varied as the hundreds of tribes, but members of these groups have one thing in common: they are under constant pressure from the major organized religions. Some of this pressure is intentional, as outside missionaries work among tribal groups to gain converts. Most of the pressure, however, comes from the process of integration within a national political and economic system that brings tribes into increasing contact with other groups and different, prestigious belief systems. In general, those tribes that remain geographically isolated in desert, hill, and forest regions or on islands are able to retain their traditional cultures and religions longer. Those tribes that make the transition away from hunting and gathering and toward sedentary agriculture, usually as low-status laborers, find their ancient religious forms in decay and their place filled by practices of Hinduism, Islam, Christianity, or Buddhism.
One of the most studied tribal religions is that of the Santal of Orissa, Bihar, and West Bengal, one of the largest tribes in India, having a population estimated at 4.2 million. According to the 1991 census, however, only 23,645 people listed Santal as their religious belief.
According to the Santal religion, the supreme deity, who ultimately controls the entire universe, is Thakurji. The weight of belief, however, falls on a court of spirits (bonga ), who handle different aspects of the world and who must be placated with prayers and offerings in order to ward off evil influences. These spirits operate at the village, household, ancestor, and subclan level, along with evil spirits that cause disease, and can inhabit village boundaries, mountains, water, tigers, and the forest. A characteristic feature of the Santal village is a sacred grove on the edge of the settlement where many spirits live