I would like to comment on this issue from a slightly different
perspective. Several years ago I was at an interdisciplinary
retreat. Over lunch a colleague in political science happened
to mention that when he lectured to students on the current
situation in former Yugoslavia, he drew an analogy between the
warring factions there (ethnic/nationalist groups??) and tribes in
Africa.
A Croatian visting professor in international relations
objected strongly but politely that the factions in Yugoslavia
were definitely NOT tribes. I then interjected that there was
a growing sentiment in academic circles that to use the term
"tribe" to refer to African groups may also be problematic.
One thing that post-modern theory has taught us (I think)
is that language is fraught with political significance. I too
favor trashing the term "tribe" because it carries a
connotation of submission/weakness.