It was a big city with no domain present. Since the Demon King Domain involved the whole region, there were cities inside it. A city could be very big and was divided into several small towns. Some were divided according to the direction: North, South, East, and west.
The noblemen were usually in some special cities. A common city had one or even two noblemen.
As for Bailan City, there was one nobleman staying here. The nobleman was a person with the highest status in a country after the king. Though there were many noblemen in a country, the land of a nobleman was so vast that one could hardly imagine.