Short for 六四天安門事件 (rokushi Ten'anmon jiken, “June 4 Tiananmen incident”).

event, incident / matter, affair / scandal

incident, event

Tian'anmen

important, significant

importance, consequence, significance

history / the study of history

(historical or contemporary) any of several kingdoms, empires, or states of the Chinese people

the central part of a country, historically, commonly known as the capital city or the main region, where an emperor or other ruler resides / something within a country

Short for 中国地方 (Chūgoku chihō): the Chūgoku region of Japan