I think that no borders are needed (ideally, but not now, because people are not ready yet). We all have from birth that which unites us - this is conscience. We all always understand what is right and what is not, because conscience cannot be deceived. If all people adhered to this, then everyone would be fine. But at the moment we are in a society of consumption and personal gain. And sooner or later this will change, since such a society leads to human degradation.