the twentieth century gives a sense of how unclear the distinction between tribal and nontribal can be. India's 1931 census enumerated 22 million tribal people, in 1941 only 10 million were counted, but by 1961 some 30 million and in 1991 nearly 68 million tribal members were included. The differences among the figures reflect changing census criteria and the economic incentives individuals have to maintain or reject classification as a tribal member. These gyrations of census data serve to underline the complex relationship between caste and tribe. Although, in theory, these terms represent different ways of life and ideal types, in reality, they stand for a continuum of social groups. In areas of substantial contact between tribes and castes, social and cultural pressures have often tended to move tribes in the direction of becoming castes over a period of years. Tribal peoples with ambitions for social advancement in Indian society at large have tried to gain the classification of caste for their tribes. On occasion, an entire tribe or part of a tribe joined a Hindu sect and thus entered the caste system en masse. If a specific tribe engaged in practices that Hindus deemed polluting, the tribe's status when it was assimilated into the caste hierarchy would be affected. Constitutional safeguards for Scheduled Tribes A number of constitutional and juridical safeguards for Adivasi have been encoded. Particularly vulnerable tribal groups The Scheduled Tribe groups who were identified as more isolated from the wider community and who maintain a distinctive cultural identity have been categorised as "Particularly Vulnerable Tribal Groups" (PVTGs) previously known as Primitive Tribal Groups by the Government at the Centre. So far 75 tribal communities have been identified as 'particularly vulnerable tribal groups' in 18 States and UT of Andaman & Nicobar Islands of India. These hunting, food-gathering, and some agricultural communities have been identified as less acculturated tribes among the tribal population groups and in need of special programmes for their sustainable development. The tribes are awakening and demanding their rights for special reservation quota for them. Notable Adivasis Kaluram Dhodade Academics Motiravan Kangali (1949–2015) – Linguist Sonajharia Minz - Computer Scientist Pandit Raghunath Murmu – Ol Chiki (Santali) script creator, writer, activist Lako Bodra – Varang Kshiti script creator, writer, activist Rohidas Singh Nag -Mundari Bani script creator, linguist Mahendra Nath Sardar - Ol Onal (Bhumij) script creator, writer Ganga Sahay Meena - Founder Editor