@michela,
These 'nations' are what they call 'imagined communities'. Really, in everyday life, we know about three hundred people, but we have been taught to identify with millions we'll never even meet. They have a legal existence as long as we choose to obey their laws, but otherwise they are just a way of thinking about ourselves, and a way that's getting pretty tatty. The way to get free of this crap is to know that WE are the only judges who count - at least for us.