seinerzeit means “back then” | MotiTan German Dictionary

More examples

Seinerzeit war ich noch Student.

Back then, I was still a student.

A pointer on a timeline aimed at an earlier period, viewed from the present.

damals: At that time, as commonly expressed in everyday speech.
früher: Before now, especially across an earlier and relatively broad period.

Zu jener Zeit in der Vergangenheit; damals

Seinerzeit developed from Middle High German sîner zît, a genitive phrase meaning 'at that time' that later fused into an adverb.

Seinerzeit is more formal and retrospective than everyday damals, so it is especially common in written narrative and reporting.