admin_government_reset_effect

admin_government_reset_effect = {
	if = {
		limit = { is_landed = yes } # error suppression
		### NOMADIC
		if = {
			limit = {
				OR = {
					government_has_flag = government_is_nomadic
					capital_province = {
						OR = {
							has_holding_type = nomad_holding
							has_holding_type = herder_holding
						}
					}
				}
			}
			change_government = nomad_government
		}
		### TRIBAL - are all of your holdings Tribal?
		if = {
			limit = {
				NOT = {
					any_held_title = {
						trigger_if = {
							limit = { tier <= tier_county }
							title_province ?= {
								NOT = { has_holding_type = tribal_holding }
							}
						}
						trigger_else = {
							title_capital_county.title_province ?= {
								NOT = { has_holding_type = tribal_holding }
							}
						}
					}
				}
			}
			assign_tribal_governments_effect = yes
		}
		else = {
			assign_feudal_governments_effect = yes
		}
	}
}

As written in game/common/scripted_effects/07_dlc_ep3_scripted_effects.txt.