How can I see what year scripted events will occur?

For example, Mongol Invasion, Gunpowder, Black Death - these are all events that will happen in every game. How can I see when they will occur in any specific game? Or if it is random, can I see a specific range?

I'm curious if it is something moddable. For one thing, I'd like the Black Death to stick around a lot longer. :)