If the tribe is known for ganking/griefing, KOS everything, no.
But my guesstimate is there will be quite a few tribes that will welcome people for trade, quests, and just chat, and will let you pass through if you are in good relations with the tribe, or, well, just dont cause any trouble on tribe territory (or in open world). You reap what you sow.
I like the mechanic, it has certain...community building...quality...attached to it.