Starting point is to have strong group with close connected members. You call it tribe. In my case, from my experience that “Tribe” is best to be made from blood relatives. Of course if that is not possible it can be made from close and good friends, but it is process that take time.
Alliances between groups or tribes like you mentioned it are possible,I mentioned alliances in order to make street security and similar, but that was very loosely, and based on circumstances.
Everything is possible to consider once when you have good organized group.