There can only be a relatively dominant tribe if 1. The smaller tribes refuse to join with the larger tribe or 2. The larger tribe refuses to accept the smaller tribes.
regarding 2: there's some nuance needed for what it means to "accept" the smaller tribes -- on whose terms? (Which leads directly to 1 -- if the larger tribe's terms are onerous, unfair, or oppressive, the smaller tribe should reject integration.)
A friend of mine is at an institution which has just started a "diversity" initiative to get people with different ethnic backgrounds in to the institution. But it's unclear whether they're willing to accept different perspectives, or whether they're really just looking for people who think the same but have different external appearances. Does it really make sense to join a "tribe" that wants to wipe out your distinctiveness and make you think and act just like they already do?
Both are bad and should be rejected.