A Period is the largest subdivision of the history. It is very large chunk of time, usually decades or centuries depending on the history, like an era of feudal wars or stellar colonization.
To make a Period:
- Decide when it is: Place the new Period between any two adjacent Periods. State which Period is earlier and which is later.
- Describe the Period: Give the other players a grand summary of what happens during this time or what thing are like. Describe how it is different from other Periods around it, as appropriate.
- Say whether it is Light or Dark: Explain how that Tone fits your description. You’re never wrong about Tone, but you do have to justify your choice to the other players.
The world can change drastically from Period to Period. Kingdoms can rise and fall, and whole technologies or schools of thought can be discovered or lost.
Your description can include how the new Period relates to the Periods around it. But even if you visualize your Period as coming right before or after another Period, someone else can add a Period in between them later on, so long as their description of their Period doesn’t contradict what was already said.
Note that you don’t specify how long a Period is. Your description may include a broad sense of how much time is passing (“It’s a war that rages for generations” or “this is decades after the revolution”), but never count years or worry about exactly how long something is.