The Royal Court (colloquially known as The Kingdom) were one of the oldest, most successful, and safest "nations" located in The BackHalls.
History
It was said that at some point in the BackHalls' impossible history, the Queen of the Royal Court owned all of the halls, or somehow had claimed all of the rooms. However, the Kingdom was primarily known to only operate a small portion of space just off of room 999.
Finding the Kingdom was as easy as traveling through the BackHalls and tracking the numbers on the floor as they get higher and higher. The Kingdom, in that regard, was the "reward" to creatures who could survive and make it all the way to the end.