The term 'Bygone Period' refers to a time in the PAST that is no longer relevant. The crossword solutions for this term are YORE (4 letters), ERA (3 letters), and PAST (4 letters). YORE is an old-fashioned word used to refer to a period of time in the distant PAST, usually associated with a particular event or ERA. An ERA is a period of time marked by a particular set of characteristics or events. The PAST is a term used to refer to any time before the present. All three words can be used to describe a Bygone Period.