Answer:Specific timeline
Explanation:A historical era is a specific time frame historians have classified due to commonalities within that time frame. Common eras include the Great Depression, the 'Roaring Twenties,' the Progressive Era, the Cold War Era, and numerous others. Ancient Era Prehistoric Era (pre-600 B.C.E.)
Classical Era (600 B.C.E.to 476 C.E.)
Post-Classical Era Middle Ages (476 C.E. to 1500 C.E.)
Modern Era Early Modern Era (1500 C.E. to 1750 C.E.)