The word tribe is variously used in literature to denote a community on the basis of homogeneity. Originally many autochthonous communities who were identified by similar culture, social organisation and governance, living away from the main stream life of a country, were mentioned as tribe by their colonial rulers and Western scholars. Many such communities have moved towards the mainstream lifestyle so that they may no longer be identified as secluded, underdeveloped people with queer customs. This has happened to all areas of the world where tribal communities live. Still, many tribal communities lead their lives in very primitive ways devoid of the techno-economic glamour of contemporary civilization. These communities are labeled as "Primitive Tribal Groups". Indian Government has identified such tribal groups to give special attention to their development, whereas in the Indian Constitution all the tribal groups are recognized as "scheduled tribes".