The most common Korean word for “old times” is 옛날 (yennal). 「old times」는 한국어로 옛날.
Learn 옛날 free — flashcards, audio and review →「옛날」 단어장으로 무료로 외우기Words and levels: TOPIK I essentials (National Institute of Korean Language standard curriculum, KOGL Type 1) · examples: Cheesepotato