The term 'PART OF HISTORY' can be represented by two crossword solutions: ERA and AGO. ERA is an abbreviation for a period of time in history, usually lasting hundreds or thousands of years. AGO is an abbreviation for the phrase 'a long time AGO, ' which is used to refer to a past event or time period. Both terms are used to refer to events or periods of time that have already passed and are now part of history.