noun, feminine/is.twa.ʁ‿ɑ̃.sjɛn/
ancient history (period of history generally seen as occurring before the Middle Ages, that is, before the fall of the Roman Empire); water under the bridge, ancient history (that which happened a long time ago and not worth discussing any more)
“C'est de l'histoire ancienne.” — That's ancient history.
Synonyms: Antiquité