pockets is in found in the region containing the Nilgiris district of Tamil Nadu, Wayanad district of Kerala and nearby hill ranges of Chamarajanagar and Mysore districts of southern Karnataka. Further south, only small pockets of tribal settlement remain in the Western and Eastern Ghats. The scheduled tribe population in Jharkhand constitutes 26.2% of the state. Tribals in Jharkhand mainly follow Sarnaism, an animistic religion. Chhattisgarh has also over 80 lakh scheduled tribe population. Assam has over 60 lakh Adivasis primarily as tea workers. Adivasis in India mainly follow Animism, Hinduism and Christianity. In the case of Bangladesh, most Adivasi groups are found in the Chittagong hill tracks along the border with Myanmar, in Sylhet and in the Northwest of Bangladesh. In Sylhet and in the north west you can find groups such as the Sauria Paharia, Kurukh, Santal, Munda and more, and other groups such as the Pnar, Garo, Meitei, Bishnupriya Manipuri and more. In the Chittagong Hill tracts you can find variouse Tibeto-Burman groups such as the Marma, Chakma, Bawm, Tripuri, Mizo, Mru, Rakhine and more. In Bangladesh most Adivasis are Buddhists who follow the Theravada school of Buddhism, Animism and Christianity are also followed in fact Buddhism has affected Adivasis so much that it has influenced local Animistic beliefs of other Adivasis. History Origin Though claimed to be the original inhabitants of India, many present-day Adivasi communities formed after the decline of the Indus Valley civilisation, harboring various degrees of ancestry from ancient hunter-gatherers, Indus Valley civilisation, Indo-Aryan, Austroasiatic and Tibeto-Burman language speakers. Only tribal people of Andaman Islands remained isolated for more than 25000 years. Ancient & medieval period According to linguist Anvita Abbi, tribe in India are charterised by distinct lifestyle and are outside of caste system. Although considered uncivilised and primitive, Adivasis were usually not held to be intrinsically impure by surrounding populations (usually Dravidian or Indo-Aryan), unlike Dalits, who were. Thus, the Adivasi origins of Valmiki, who composed the Ramayana, were acknowledged, as were the origins of Adivasi tribes such as the Garasia and Bhilala, which descended from mixed Rajput and Bhil marriages. Unlike the subjugation of the Dalits, the Adivasis often enjoyed autonomy and, depending on region, evolved mixed hunter-gatherer and farming economies, controlling their lands as a joint patrimony of the tribe. In some areas, securing Adivasi approval and support was considered crucial by local rulers, and larger Adivasi groups were