From the introduction:
Neolithic Age: You can use sticks and stones to break people's bones. A lack of harder farming implements limits stone age cultures to hunter gather sustenance living. The best defense is either caves or mobility. No real tools beyond sticks, stone knives, and spears.
Presents resources for several historic periods of play, including: Neolithic Age, Age of Ancients, Classical Age, Imperial Age, Ax Ages, and Age of Crusades.