From Longman Dictionary of Contemporary Englishin (the) olden daysin (the) olden days (also in olden times)PAST a long time ago People didn’t travel so much in the olden days. → olden
Examples from the Corpus
in (the) olden days• Mainframes were bought by Data Processing Managers in the olden days.• We never used to have wind and rain during autumn in the olden days.• In the olden days, players didn't wear numbers on their jerseys.• What we used to do - you know in the olden days, the ladies used to use stays.• Often in olden days would I be lifted up, and up, and up, for the sake of my plays. 