Many societies in the subcontinent did not follow the social rules and rituals prescribed by the Brahmanas. Thus, they were not divided into numerous unequal classes. Such societies are often called tribes. Some of its characteristics are:
1. Members of each tribe were united by kinship bonds. They were mainly agriculturists from hunter-gatherers or herders. Most often they combined these activities to make full use of the natural resources of the area in which they lived. 2. Some tribes were nomadic and moved from one place to another. 3. A tribal group controlled land and pastures jointly, and divided these amongst households according to its own rules. 4. They usually lived in forests, hills, deserts and places difficult to reach from the mainlands. 5. They retained their freedom and preserved their separate culture. 6. The caste-based and tribal societies also depended on each other for their diverse needs. This relationship, of conflict and dependence, gradually caused both societies to change.

This video explains what tribes are.

Some of the learners also asked:
How the members of each tribe are united?