settle_the_people_vassal_effect

settle_the_people_vassal_effect = {
	nomad_domicile_refund_effect = yes
	nomad_convert_herds_to_gold_special_troops_effect = yes
	if = {
		limit = {
			any_held_title = {
				is_nomad_title = yes
			}
		}
		every_held_title = {
			limit = {
				is_nomad_title = yes
			}
			root = {
				destroy_title = prev
			}
		}
	}
	if = {
		limit = {
			scope:new_capital.title_province = {
				has_holding_type = tribal_holding
			}
		}
		assign_tribal_governments_effect = yes
	}
	else = {
		assign_feudal_governments_effect = yes
	}
	change_authority_effect = { CHANGE = 1 }
}

As written in game/common/scripted_effects/09_dlc_mpo_scripted_effects.txt.