Whats the deal with the Elswyr and Valenwood part of the map. Its a vast area and you can build on it the construstion set but you can't play in it. Is there some reason why its blocked["Can't go this way, turn back."], Is there a way to unblock it.

Controlled by region borders. Believe there are already several mods that try to make use of those areas.

And.... you don't want to see 'the end of world' when you reach the border.