Prosperity can be anywhere from 0-100.
Increases in Prosperity
The following events will raise the prosperity of a town:
- A caravan coming from another town arrives at this town.
- A group of farmers from a village arrives at its destination.
- If the prosperity of a town is low, solving shortages of items will cause the prosperity of a town to gradually rise.
The following factors attract caravans to a town:
- This town has a trading route to where a caravan was last at.
- There are lots of shortages of items in this town, compared to where the caravan was last at.
The following events will raise the prosperity of a village:
- A group of farmers from the village returns from its destination.
- The player completes an economic quest for the village.
- The player purchases items or cattle from the village.
- The player builds a mill in the village.
- If the prosperity of a village is low, solving shortages of items will cause the prosperity of a village to gradually rise.
- The prosperity of a castle starts as the prosperity of its village.
- The prosperity of a castle always tends to 65 in the long run.
Decreases in Prosperity
The following events will lower the prosperity of a town:
- The town is besieged.
- Shortages of items will cause the prosperity of a town to gradually lower.
- If the prosperity of a town is high, the prosperity of a town will gradually lower.
The following events will lower the prosperity of a village:
- The village is attacked or infested by bandits.
- Shortages of items will cause the prosperity of a village to gradually lower.
- If the prosperity of a village is high, the prosperity of a village will gradually lower.
A raid will reduce a village's prosperity by 60, up to a minimum value (mills increase this value).
- The castle is besieged.
As long as a town or castle is under siege, they will have a 33% chance to lose 1 prosperity every 24 hours. If they are conquered, they will lose 5 points of prosperity.
Supply and Demand
All towns and villages have an internal supply and demand system for every item, regardless if they sell it to the player. Each town and village has a semi-randomly determined amount of production and consumption for each item. These production and consumption amounts may temporarily change in the event of very high prices.
Producing too much of an item will cause the price to drop while consuming too much of an item will cause the price to rise and a shortage of an item to form.
Trading from villagers and caravans always happens one way. From the origin to the destination. The destination items move slightly closer (3% per visit for villagers, 4% per visit for caravans) to the prices/supply of the origin. This has the affect of balancing supply and demand among frequent trade partners like a town and its villages.
Towns may have a slower increase in prosperity because their supply will be more likely to be drained by multiple villages than vice versa. Their production and consumption numbers will also be bigger and fluctuate more often which resists sudden changes unlike villages. Additionally, in determining how items shortages can reduce prosperity, towns are more sensitive to shortages and to more varied types of item shortages than villages. Shortages in certain goods like Velvet and Spice disproportionately affects towns compared to villages. Resulting in villages that thrive through these shortages while towns suffer.