Related Clues:
- Presidential terms, perhaps
- Fashion periods
- Meaningful stretches of history
- Pleistocene and Eocene, for two
- Time-line slices
- Cenozoic and Big Band
- Interesting historical periods
- Time passages
- Important considerations in Cy Young Award voting
- Memorable periods of history
- '-zoic' periods
- Presidencies may define them
- Stylistic periods
- Victorian, Romantic, etc
- Lengthy reigns, say