Quote Originally Posted by brian 333 View Post
Combat in D&D allows characters ten or more levels higher than their foes to wipe out virtually any number of them. See Belkar's Sexy Shoeless God of War moment.

I assume Oona's tribe is advanced beyond normal 3HD bugbears, but they would have to be level 12 or so to have any real chance to succeed in an attack, and be willing to accept significant losses to do it.
They are a tribe of dungeon crawling adventurers, hunting monsters as a living. I wouldn't be surprised if they have impressive PC levels.