assign_new_government_effect

assign_new_government_effect = {
	if = {
		limit = {
			exists = scope:new_capital
			NOT = { exists = scope:capital_county }
		}
		scope:new_capital = { save_scope_as = capital_county }
	}
	save_scope_as = new_ruler
	# Change our government according to the government of our liege.
	## Nomad.
	if = {
		limit = {
			scope:capital_county.title_province = {
				OR = {
					has_holding_type = nomad_holding
					has_holding_type = herder_holding
				}
			}
		}
		hidden_effect = {
			every_held_title = {
				title_tier = county
				limit = {
					title_province ?= { has_holding_type = herder_holding }
				}
				title_province = { set_holding_type = nomad_holding }
			}
		}
		change_government = nomad_government
	}
	## Wanua or Tribal.
	else_if = {
		limit = {
			scope:capital_county.title_province = {
				has_holding_type = tribal_holding
			}
		}
		assign_tribal_governments_effect = yes
	}
	## Mandala.
	else_if = {
		limit = {
			has_mandala_culture_trigger = yes
			has_mandala_faith_trigger = yes
			scope:capital_county.title_province = {
				has_holding_type = temple_citadel_holding
			}
		}
		change_government = mandala_government
		#Sort out the House shenanigans
		hidden_effect = {
			if = {
				limit = { is_house_head = no }
				house = {
					if = {
						limit = {
							house_head = {
								is_landed = no
								is_courtier_of = scope:new_ruler
							}
						}
						set_house_head = scope:new_ruler
					}
				}
			}
			else = {
				house ?= {
					set_house_aspiration = { type = no_aspect }
				}
			}
		}
	}
	## Administrative govs
	else_if = {
		limit = {
			OR = {
				government_has_mechanic = administrative
				exists = scope:admin
			}
		}
		change_to_administrative_effect = yes
	}
	# add check for non-playable govs?
	else_if = {
		limit = { exists = scope:old_government }
		change_government = scope:old_government
	}
	## Else feudal.
	else = { assign_feudal_governments_effect = yes }
}

As written in game/common/scripted_effects/00_government_effects.txt.