I think the circumstances in which tribalism could arise are more prevalent in a low technology situation and a cultural context that does not have the concept of nation or nationality, but is defined by ethnic or familial relationships, while in today's context of whole nations, people will seek to control the whole thing, creating a single or perhaps a series of civil wars that would be very difficult to not be caught up in, even if people sought to avoid it.
Thats pretty close to my understanding of the anthropological behaviors of people after a complete collapse. Humans actually get along pretty well in groups up to about 700, where interpersonal relationships are close enough to discourage abuses.
One thing to keep in mind, and I consider myself an anarchist, is that the common definition of anarchy=chaos came after the "original" movement. It technically means "without a king". As monarchy means "one is king", and democracy means "people are king".
Classical anarchism is REALLY interesting, and I can totally see why it became a synonym for chaos. All the best games in the world DEPEND on coercion. On the "right" to force someone to do or not do something. Anarchism says you can have all the capitalism you want, but there can be no coercion. No threat or force. I was delighted to find out how well thought out some of the ideas were.
All people everywhere who live on frontiers live in a functional state of anarchy, where no one has functional authority over anyone else. They work it out and deal with it. The more people there are the less well this works, and eventually the formal structure of some existing culture spreads into the frontier in question and replaces the existing way of doing things.
I consider myself a practical anarchist, which means I don't think human beings are "equipped" to function in an anarchic state. Some people really ARE happier leaving the decision making and responsibility taking to somebody else. Lots of people are "followers" by nature, some people NEED to lead, most fall somewhere in between. It worked for us for 100,000 years, its in our genes and all of our cultures. That said, self rule should be the ideal striven for.
Our democracy is limited because true democracy is disfunctional due to human nature. But theoretically true democracy would be the ideal.
So I support the idea of stateless self rule as the ideal being striven for, as the ultimate goal of of a democratic state, which acknowledges humankinds weaknesses and seeks to prevent concentration of power as a primary tenet.