Adivasi (Sanskrit: Nepali: Hindi: आदिवासी; ādivāsī) is an umbrella term for a heterogeneous set of ethnic and tribal groups claimed to be the aboriginal population of India. They comprise a substantial indigenous minority of the population of India. The word is used in the same sense in Nepal as is another word janajati (Nepali: जनजाति; janajāti), although the political context differed historically under the Shah and Rana dynasties.

Adivasi societies are particularly present in the Indian Tamil Nadu, Orissa, Madhya Pradesh, Chattisgarh, Rajasthan, Gujarat, Maharashtra, Andhra Pradesh, Bihar, Jharkhand, West Bengal, Mizoram, and other northeastern states, and the Andaman and Nicobar Islands. Many smaller tribal groups are quite sensitive to ecological degradation caused by modernization. Both commercial forestry and intensive agriculture have proved destructive to the forests that had endured swidden agriculture for many centuries. Officially recognized by the Indian government as "Scheduled Tribes" in the Fifth Schedule of the Constitution of India, they are often grouped together with scheduled castes in the category "Scheduled Castes and Tribes", which is eligible for certain affirmative action measures.

Verrier Elwin (29 August 1902 – 22 February 1964) was a self-trained anthropologist, ethnologist and tribal activist, who began his career in India as a Christian missionary. He was a controversial figure who first abandoned the clergy, to work with Mohandas Gandhi and the Indian National Congress, then converted in Hinduism in 1935 after staying a Gandhian ashram, split with the nationalists over what he felt was an overhasty process of transformation and assimilation for the tribals. Elwin is best known for his early work with the Baigas and Gonds of central India, and he married a member of one of the communities he studied there, though he also worked on the tribals of several North East Indian states especially North-East Frontier Agency (NEFA) and settled in Shillong later in life, apart from Orissa and Madhya Pradesh.

In time he became an authority on Indian tribal lifestyle and culture, particularly on the Gondi people. He also served as the Deputy Director of the Anthropological Survey of India upon its formation in 1945. Post-independence he took up Indian citizenship. Nehru appointed him as an adviser on tribal affairs for north-eastern India, and later he was Anthropological Adviser to the Government of NEFA (now Arunachal Pradesh).