Tribalism concerns groups of people having a common race, character, occupation, or interest. Status and ethnic or linguistic identity become linked (for example in the UK when it used to be accepted that a person with a certain accent would automatically be labelled "lower class") thus possibly leading to discrimination. Tribalism could also possibly lead to policies of ethnic chauvinism that grant advantages and privileges to an ethnic group as a whole or to certain of its members.
Tribalism is one manifestation of a force of collective assertion, aggression and defence that is also inspired by race, religion, communal identity, a communal commitment exalted in some nations as patriotism. It is the primal urge to belong to one group and hate the rest.
A tribe is a family which has grown as a result of procreation. It is a big family; it provides its members with material benefits and social advantages the family provides for its members. It is a natural social umbrella for social security, bringing up children and providing a sense of identity.