From Longman Dictionary of Contemporary Englishancient historyancient historya) the history of ancient societies, such as Greece or Rome a professor of ancient history b) informal if you say that something is ancient history, you mean that it happened a long time ago and is not important now It’s all ancient history and I’m not upset anymore. → ancient
Examples from the Corpus
ancient history• For one thing, this is not ancient history.• He was so beautiful in those days - listen to me, those days, talking like it was all ancient history.• The world of Lowry's north seems to be ancient history.• Its very imperfection is powerful testimony of its ancient history, a history of step-by-step change rather than of deliberate design.• It has been fashionable in the last twenty years to suggest that there was in ancient history a utopian matriarchy.• Will and I broke up a long time ago - that's ancient history now.• That, too, seemed like ancient history now.• He was very fond of ancient histories, stories and epics of earlier times and heroes.• But my tale of ancient history was less than a generation old. 