The Schlei Domain is not large, with the religious district, administrative district, and commercial district being the core of the Western City, a rare prosperous area in the territory...however, it still only has a population of around 20,000 to 30,000 people.
The so-called "city-states" in this era are vastly different from the cities that most people are familiar with.
In a feudal, agrarian society, most people are trapped in their farmland, and small towns or even villages are the primary social forms where 99% of the population resides.
A city-state? In truth, the small city of an ordinary lord is merely a slightly larger "rural market."
Villagers, farmers, and townspeople only go to the city to sell vegetables or buy some necessities when necessary, and the frequency of replacing living materials is mostly calculated on an annual basis.
The core area of the Schlei Domain is probably only a little more populated than the "towns" that the visitors are familiar with.