tribute_mission_decision_ai_potential_trigger

tribute_mission_decision_ai_potential_trigger = {
	is_at_war = no
	faith = {
		prev != religious_head
		NOT = { exists = great_holy_war }
	}

	# Emperors are much more selective
	trigger_if = {
		limit = { primary_title.tier >= tier_empire }
		tribute_mission_decision_ai_religion_culture_limit_trigger = { TARGET = $TARGET$ }
	}

	#Pace the AI
	trigger_if = {
		limit = {
			is_tributary = yes
			NOT = { has_variable = requested_tribute_mission }
		}
		suzerain = { NOT = { has_character_flag = pay_tribute_cooldown } }
		NOT = { has_variable = tribute_mission_grace }
		$TARGET$ ?= { NOT = { has_variable = ai_tribute_mission_cooldown } }
	}
	NOR = {
		any_owned_story = {
			OR = {
				story_type = story_mongol_invasion
				story_type = story_greatest_of_khans
			}
		}
		mpo_has_gok_mongol_empire_trigger = yes
		has_trait = conqueror
		has_trait = greatest_of_khans
		is_gurkhan = yes
	}
}

As written in game/common/scripted_triggers/tgp_tribute_mission_triggers.txt.