Vassal State must control at least three or more towns.
Kingdom must possess one State Mansion + at least four towns.
Empire requires at least five State Mansions and 20 towns.
Aside from territories and population, another important metric is the Country Influence Value.
This Influence Value divides into King's Path Value and Overbearing Value.
By expanding territories, capturing lands, conquering through slaughter, and competing for territories with NPCs, you can acquire Overbearing Value.
Gathering refugees, recovering villages and towns from Monster Forces, clearing monster nests, and reducing the danger levels of the map can increase the King's Path Value.
When the Overbearing Value or King's Path Value reaches 100%, it triggers the mission for the country's upgrade, upon meeting other upgrade conditions, the country level can then be raised.
Different development routes will result in different types of political changes when the country upgrades.
