Because the map is so huge, you might not be able to conquer the world in one lifetime, hence make sure you groom your heirs well so that you have someone to succeed you. When you united and conquered Calradia, the map will change to a world view where there are 7 other kingdoms the size of yours and you get to travel via sea towards the west and north and via land towards the east and south to new lands and try to do a world domination.
