tgp_dynastic_cycle_record_history_phase_change_effect

tgp_dynastic_cycle_record_history_phase_change_effect = {

	# protect from double history entries
	if = {
		limit = {
			situation:dynastic_cycle = {
				OR = {
					NOT = { exists = var:last_recorded_phase_change }
					AND = {
						exists = var:last_recorded_phase_change
						OR = {
							var:last_recorded_phase_change != $PHASE_NUMBER$
							var:last_recorded_phase_change = 4
						}
					}
				}
			}
		}
		# When we enter Division, we only want to show the old hegemon
		if = {
			limit = {
				situation:dynastic_cycle = {
					situation_current_phase = situation_dynastic_cycle_phase_chaos
				}
			}
			situation:dynastic_cycle = {
				record_situation_special_event = {
					key = situation_dynastic_cycle_era_change_history_entry
					phase = $PHASE$
					variables = {
						old_hegemon = title:h_china.previous_holder
					}
				}
			}
		}
		# When we restore China after division, we only show the new hegemon
		else_if = {
			limit = {
				#exists = title:h_china.holder
				#title:h_china.holder = { is_valid_celestial_dynasty = yes }
				situation:dynastic_cycle = {
					exists = var:last_recorded_phase_change
					var:last_recorded_phase_change = 6
				}
			}
			situation:dynastic_cycle = {
				record_situation_special_event = {
					key = situation_dynastic_cycle_era_change_history_entry
					phase = $PHASE$
					variables = {
						new_hegemon = title:h_china.holder
					}
				}
			}
		}
		# If we replace the ruling dynasty, show new and old hegemon
		else_if = {
			limit = {
				exists = title:h_china.holder
				exists = title:h_china.previous_holder
				title:h_china.holder.dynasty != title:h_china.previous_holder.dynasty
			}
			situation:dynastic_cycle = {
				record_situation_special_event = {
					key = situation_dynastic_cycle_era_change_history_entry
					phase = $PHASE$
					variables = {
						new_hegemon = title:h_china.holder
						old_hegemon = title:h_china.previous_holder
					}
				}
			}
		}
		# Else, show none
		else = {
			situation:dynastic_cycle = {
				record_situation_special_event = {
					key = situation_dynastic_cycle_era_change_history_entry
					phase = $PHASE$
				}
			}
		}
		situation:dynastic_cycle = {
			set_variable = {
				name = last_recorded_phase_change
				value = $PHASE_NUMBER$
			}
		}
	}
}

As written in game/common/scripted_effects/10_dlc_tgp_dynastic_cycle_scripted_effects.txt.