Brahmajala Sutta (Theravada)
In the second part, the Buddha explains the major beliefs of ascetics in India. He begins by saying, ""Monks, there are other things which are very deep (profound), very hard to understand, very difficult to perceive, so holy and sacred, unreached by means of mind, so subtle, that they are only to be understood and experienced by the wise. These things were perceived clearly, seen clearly and were discarded by the Tathagata, and by this act based on the truth that people praise and revered Tathagatha. What are those things?""
Tribal religions in India
About 104 million people in India are members of Scheduled Tribes, which accounts for 8.6 % of Indias population (according to the 2011 census). Many Indians belonging to these populations adhere to traditional Indian tribal religions, often syncretised with one or more of the major religious traditions of Hinduism, Buddhism, Islam and/or Christianity and often under ongoing pressure of cultural assimilation. In keeping with the nature of Indian religion generally, these particular religions often involve traditions of ancestor worship or worship of spirits of natural features. Tribal beliefs persist as folk religion even among those converted to a major religion.