Recent economic developments and political rivalries will loom much larger than allegedly ancient and traditional hostilities. Ironically, some African ethnic identities and divisions now portrayed as ancient and unchanging actually were created in the colonial period. In other cases earlier distinctions took new, more rigid and conflictual forms over the last century. The changes came out of communities' interactions within a colonial or post-colonial context, as well as movement of people to cities to work and live. The identities thus created resemble modern ethnicities in other countries, which are also shaped by cities, markets and national states.
Tribe substitutes a generalized illusion for detailed analysis of particular situations.
The bottom-line problem with the idea of tribe is that it is intellectually lazy. It substitutes the illusion of understanding for analysis of particular circumstances. Africa is far away from North America. Accurate information about particular African states and societies takes more work to find than some other sorts of information. Yet both of those situations are changing rapidly.