I don't know about tribes but it's certainly the case in any poly relationship.
Biggest reason my former triad fell apart was because M had this natural urge to be a ringmaster so to speak, being the oldest and the one who owned the house and the one that brought us all together. He let it go to his head and after three years just became downright bossy. C had a rebellious "nobody tells me what to do" attitude and eventually the whole thing erupted like a split atom. (And me, trying to be the passive peacemaker, left with PTSD.)
Since then I've warned anyone I know getting into a poly situation to make sure there's a cap on the number of alpha males. More than one, and you got a recipe for explosions.
Now, I've been dating for 9 months a guy who is mostly as laid-back as me. Much better and tons less stressful! (Though there are some issues cuz he's still not used to poly, but that's another thread for another day.)