Regions are split into one of 4 region types
1)
Faction capital
2)
Province capital
3)
Minor region
4)
Frontier region (bordering any other faction's region)
Different
influencers then make different region types more desirable
1)
food shortage - sends pops of all types to minor regions
2)
Treasury - a large faction treasury draws all pops to the faciton and to a lesser extent province capitols to try get their hands on some of it
3)
losing money - people go to minor settlements
4)
war - when at war people flee the frontier regions
5)
sea trade route raided - pop goes to minor regions
6)
faction - different factions can have more likelihood to be ruralised or urban
7)
tax level - people flee to frontiers with high tax to avoid the tax man
8)
not researching - stagnant culture will result in people leaving capitols and going to minor regions
9)
number of allies - reduces penalty in frontier regions
10)
Class ratios - The faction will have an ideal population class ration if the regions pop ratio is different to the ideal then it will get a bonus or malus to bring it into line with the ideal base ratio. This is a multiplier applied to all other immigration influences and as such should have the largest impact on immigration movements in most cases.
11)
Undersiege - all pops will want to leave a settlement undersiege
12)
foreign army present: all pops will leave
13)
battle fought - all pops will want to leave a region where a battle is fought
14)
buildings - can give a bonus to a regions migration attractiveness and it can vary for region type. Currently no buildings give a bonus but the mechanic is set up to allow it to be added.
15)
technologies - just like buildings, tech also can impact region migration attractiveness. Currently no techs give a bonus but the mechanic is set up to allow it to be added.
How
Migration Movements Work
Each region gets a migration attractiveness/desirability rating. These are then compared against all the neighbouring regions owned by the faction. If the neighbour region is more desirable, then it will get a boost to its population and the less desirable region will lose population
People can only migrate to an adjacent region. This means that island regions will only have inter island migration.