Related Clues:

• Slice of history
• Period
• Initiates
• Brand at the laundromat
• Roaring Twenties, e.g.
• Time period
• Stretch of history
• Part of B.C.E.
• The Thatcher years, e.g., in Britain
• Laundry detergent brand
• Historic time
• See 30-Across
• Stat for Clemens
• See 54-Down
• Commences