From the interior of Sardinia to central Germany and Ireland, there is a lot of land that is uncolonized and seemingly empty on the political view. They do, however, have pops with their own religions and cultures. Colonization and Settling are the two ways countries can take control of these lands.
A city is colonized by moving one pop of any social class but slaves to it. This can be achieved either by pressing the colonization button in city view or simply by moving it there from the "move to-menu. This can be done any time, as far as following conditions are met:
The city from which the colonization is done must:
- be adjacent to the city being colonized
- have at least 10 pops (no matter their social class)
- majority of the population must have state's culture and religion
- the colonizing pop must be of your national culture and religion and must not belong to the slave social class
Tribal chiefdoms have the ability to turn all pops (min 3, max 20) in a city into migration units, for a base cost of -8 Stability (Certain laws and your level of centralization modify this number). These Light Infantry units can settle in any uncolonized location as long as they outnumber the existing pops. When settled, they always turn into Tribesmen. Like colonization, all pre-existing pops are kept with their culture, religion, and types.
Migration units do not require military access to cross borders, and enjoy reduced attrition. Settling also works with foreign land a tribe currently controls in a war.