- The ages (based on precession of the equinoxes) are named after astrological signs;
- They are arranged in reverse order (Age of Aquarius follows Age of Pisces;)
- The ages are about 2100 years long each.
Next, we pick an arbitrary start point for the Age of Pisces: 200 BC. This jibes somewhat with JB's belief that the Age of Aquarius started in the early 20th century. But more importantly, we can now take a look backwards at the previous ages:
- Age of Aries (2300 BC to 200 BC): most of the Bronze Age stuff we're familiar with takes place here.
- Age of Taurus (4400 BC to 2300 BC): the time of Uruk, megalith builders, the start of the Minoan civilization, and the Egyptian Old Kingdom.
- Age of Gemini (6500 BC to 4400 BC): Copper Age in Middle East, Stone Age everywhere else.
- Age of Cancer (8600 BC to 6500 BC): Stone Age, all the way down...
You could take these rough cultural associations, with or without anachronistic medieval technology, plus any associations you may have with pop astrology or just the symbols themselves (Ram, Bull, Twins, Crab) and create your own easy-to-remember chronology for your fantasy world. The Age of the Ram seems like a good symbol for individualistic, head-strong heroes carving out their own kingdoms or trade routes. Figure there's a short period of strife and instability in between each age, so your campaign world would have memories of recent "Dark Times" and visible ruins of the Empire of the Bull, but only vague legends of the distance Age of the Twins or Age of the Crab. Perhaps the Age of the Crab would be the zenith of an aquatic empire, ruled by mermen or any other aquatic species you'd like.