One tribe, one valley, one plain, one state, one nation, one continent, one Earth.
Entities with a lot in common tend to control their common interests, and common interests seem to join together to create an entity.
As time goes on I think we'll either decend into barbarity, or come to realize there is one Earth, and that's enough in common to create a entity which governs matters of worldwide concern.
And there will come to be more and more of them. But all that is a long, long ways off.
Arf