It is intentionally left vague. If i recall right the Age of Ice lasted between 300-1000 years, the Age of Magic likely even longer, and the Age of Dragons and Age of Creation... entirely speculative. I think it's to avoid being hemmed in and forced to ridigly conform to a timeline.
Managed to install it fine, but how the hell do you get any gold in this game? I built a mine on a tile with gold and a road from it to my city, still losing 2 gold a turn, exactly the same as before i built it.