Ancient history
01
古代史, 古代世界の歴史
a history of the ancient world
02
古代史, 昔の話
knowledge of some recent fact or event that has become so commonly known that it has lost its original pertinence
03
古代史, 遠い過去
something that occurred a long time ago and is now considered irrelevant or unimportant
Informal
例
The rumors from high school are ancient history; no one even remembers them anymore.
高校時代の噂は昔の話で、もう誰も覚えていない。
