As an aside on that kind of tribalism.
There is a valley on Africa where scientists have discovered the remains of multiple neolithic tribes inhabiting it long term in caves. The men all have markers indicating that they grew up in the valley.
All of the adult women do not.
Yes. Notably, it seems like the same behaviours exist in Bonobos and in Chimpanzees.
In bonobos it is the young males that leave/are exiled from the group, and in Chimpanzees it is the young females.