The Dark Ages: a historical or metaphorical period when culture or civilization declined; equivalent to 'Dark Ages'.
中世ヨーロッパの暗黒時代について学校で習った。
I learned about the Dark Ages of medieval Europe at school.
戦争の影響でこの地域は暗黒時代のような状況になった。
Because of the war, the region fell into a situation like a dark age.
技術革新前の長い暗黒時代が文化に与えた影響を研究する。
Researchers study the effects of the long dark age before technological innovation on culture.
A period of decline or stagnation; used figuratively in everyday speech to refer to a very difficult period.
あの会社は一時、暗黒時代を経験したが、経営改善で再生した。
That company once experienced a dark period but was revived through management reforms.