大昔に

long ago

→ 大昔
phrase Rare #38,073
long ago Used to refer to a very distant time in the past; に marks the time when something happened.
JA: 大昔に、この山には大きな湖がありました。
EN: Long ago, there was a large lake on this mountain.

ペテルブルグ銀行大昔に襲ったさえもするんじゃない

Don’t even tell the story about that time you robbed a bank in Petersburg, way back when.

— レザボア・ドッグス (1992)

恐竜大昔に絶滅した

Dinosaurs went extinct a very long time ago.

母は大昔に亡くなり昨年亡くなりました

My mother died a very long time ago—and my father passed away last year.

— レベッカ (1940)

人間は大昔に道具の使用を覚えた

Humans learned to use tools long ago.