The purpose is that you need a population to be a city.
It was the case that a city needed 20,000 people to be called a city.
I can imagine that the people that live in the houses belong to the governors and mix with other people belonging to other governors in that place/field.
They present a world of real history and bring fresh challenges to the game. If someone attacks the field they attack several governors at the same time.
The people should travel to the city/castle for safety. The people existing, gives a purpose to the city.
It also gives fertile ground for start-ups to raid. Or robbers to rob.
The slot has a settler count and a house count. To build a house costs a settler and 100wood 50clay. That's all. The number of settler can be three times the number of houses.
If there are no settlers in the houses of a governor's slot, someone can move in to the houses and have the slot.
Maybe after some time a new settler comes from the house to the city. The settlers feed themselves.
If the houses are destroyed the slot becomes empty. Anyone can take a slot to build thier houses. Woe to them if they build far away. But perhaps it will be out of harms way. The houses do not show up on the map. You must investigate the field to see the houses.
*note: Belong to village/city not governor.
It would create allot more small battles where people would be more forgiving if it is attacked. It would loosen up the game. Players would not be so isolated. This added to the 'army size limit at rally point' idea I had would create a more fluid game. Perhaps the settlers in the houses can go to the city to be trained as soldiers. The point of the population.
When the people/settlers in the houses are in the village you have to feed them.
In the house field you could have five houses filing one slot. Five slots per field. With 15 people living there in each slot. They don't need feeding. You would have to make it easier to train settlers and raise the amount of settlers needed to start a new village. So if you send any less than 20 settlers they make houses. If you send more than 20 settlers they make a village and the rest come back to the village.
The amount of settlers you have in total gives you a bar to judge by. For things like prestige, village to city, tables in kingdoms, speed of building resources levels and kingdom size.
This is good because then it would be harder to keep massive cities that are impenetrable and unbeatable. It stops the top rated players getting too big, because it would make it harder to keep such a large population safe.
It would be more fun for smaller players. They can raid houses and don't need to make there own yet.
There could be a button in the town hall that automatically brings people to the city if there is an incoming attack. This could be the Town Hall Bell button. Maybe you have to pay for a golden bell using gold coins.
The houses would be visible once you click on the field, just like resource distribution.