In Atelier Meruru, the Kingdom's rank is a measure of your progress in the redevelopment of Arls. Your rank is based on how many total development points you've earned. If you visit Rufus at certain milestones, he will congratulate your progress and you'll be shown your new rank. As your rank increases, so does your population, and the availability of new development projects and requests. See a list of facilities for what can be built at each level.