tgp_tributary_setup_effect

tgp_tributary_setup_effect = {
	title:h_china.holder ?= {
		save_scope_as = suzerain

		if = {
			limit = { current_date >= 851.1.1 current_date <= 1036.1.1 }
			title:k_hexi.holder ?= {
				break_subject_contract_and_establish_tributary_effect = { SUZERAIN = scope:suzerain TRIBUTARY = this }
			}
		}
		if = {
			limit = { current_date >= 705.1.1 current_date <= 926.1.1 }
			title:k_balhae.holder ?= {
				break_subject_contract_and_establish_tributary_effect = { SUZERAIN = scope:suzerain TRIBUTARY = this }
			}
		}
		if = {
			limit = { current_date >= 337.1.1 current_date <= 935.1.1 }
			title:k_silla.holder ?= {
				break_subject_contract_and_establish_tributary_effect = { SUZERAIN = scope:suzerain TRIBUTARY = this }
			}
		}
		if = {
			limit = { current_date >= 866.1.1 current_date <= 1132.1.1 }
			title:k_dzungaria.holder ?= {
				break_subject_contract_and_establish_tributary_effect = { SUZERAIN = scope:suzerain TRIBUTARY = this }
			}
		}
	}

	if = {
		limit = { current_date >= 1178.1.1 }
		tgp_1178_tributary_setup_effect = yes
	}
	else_if = {
		limit = { current_date >= 1066.1.1 }
		tgp_1066_tributary_setup_effect = yes
	}
	else_if = {
		limit = { current_date >= 867.1.1 }
		tgp_867_tributary_setup_effect = yes
	}
}

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