Step-by-step explanation:
An era is a span of time defined for the purposes of chronology or historiography, as in the regnal eras in the history of a given monarchy, a calendar era used for a given calendar, or the geological eras defined for the history of Earth. Comparable terms are epoch, age, period, saeculum, aeon and Sanskrit yuga.
a period of time considered as being of a distinctive character; epoch. an extended period of time the years of which are numbered from a fixed point or eventthe Christian era.