What is millennia?

Answer 1

A millennium is a period of one thousand years. It is often used in historical and cultural contexts to mark significant time spans, such as the transition from one century to another or to denote major historical events. The term can also refer to the start of a new thousand-year period, such as the year 2000 marking the beginning of the third millennium. In a broader sense, "millennia" is the plural form, referring to multiple such periods.