quality:corruption, structural:reformatting
Other criteria

Unlike castes, which form part of a complex and interrelated local economic exchange system, tribes tend to form self-sufficient economic units. For most tribal people, land-use rights traditionally derive simply from tribal membership. Tribal society tends to the egalitarian, with its leadership based on ties of kinship and personality rather than on hereditary status. Tribes typically consist of segmentary lineages whose extended families provide the basis for social organisation and control. Tribal religion recognises no authority outside the tribe.

Any of these criteria may not apply in specific instances. Language does not always give an accurate indicator of tribal or caste status. Especially in regions of mixed population, many tribal groups have lost their original languages and simply speak local or regional languages. In parts of Assam—an area historically divided between warring tribes and villages—increased contact among villagers began during the colonial period, and has accelerated since independence in 1947. A pidgin Assamese developed, whereas educated tribal members learnt Hindi and, in the late twentieth century, English.

Self-identification and group loyalty do not provide unfailing markers of tribal identity either. In the case of stratified tribes, the loyalties of clan, kin, and family may well predominate over those of tribe. In addition, tribes cannot always be viewed as people living apart; the degree of isolation of various tribes has varied tremendously. The Gonds, Santals, and Bhils traditionally have dominated the regions in which they have lived. Moreover, tribal society is not always more egalitarian than the rest of the rural populace; some of the larger tribes, such as the Gonds, are highly stratified.

The apparently wide fluctuation in estimates of South Asia's tribal population through 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.