Preparing a scenario set in the past means research.

If you're not careful, you'll spend so much time doing research that you never actually do get around to preparing the scenario! There's always the sense that just one more piece of information is needed to make it authentic. Do I make up a name for the mayor of the town, or do I try and discover who really was mayor? Do I research to see what sort of problem they had in that time with stray dogs? What piece of information really will add value to the scenario?

Having run some games set in the past, I offer you these tips to make your scenario both authentic, and easier to research.

Common Info

There are some common pieces of information that come into play no matter what sort of game you're running.

Eventually some action will happen at night, and someone will ask, "Is the moon full?" Spending a few minutes looking up the phases of the moon for the time period you're using will allow you to answer that with more than just a guess. Of course, don't feel constrained to use the real phases of the moon...if your scenario calls for a full moon, then it's a full moon.

The names of the current rulers is also another piece of information that will come in handy. Especially if you're doing a time travel scenario, where the PCs may not know when they ended up. One of their first questions of the people they meet will be the local equivalent of "Who's the President?"

Find Things That Don't Make Sense

You'll come across a lot during historical research that just doesn't make sense. For example, while researching for a Call of Cthulhu time travel scenario, I found that in the time period I wanted them to travel to, the town was meeting to make a decision about forming a college. But, a local reverend who ran an academy was not involved in those discussions. I asked myself Why? That became one of the major plot lines in the scenario.

If it doesn't make sense in the historical record, think about what might not have been recorded. What secrets were hidden?

Know The Currency

Do research the currency used in the time period. That's a nice little piece of authenticity that makes the parts you make up seem real, too. Your players figure that if you went to the trouble of figuring out the denominations of money used, then the rest of the details must be real, too.

Know When Buildings Were Built

If the location is in the past of a place that your players will have knowledge of, then know when the local landmarks were built. This becomes especially important for time travel scenarios.

Make Up The Rest

Don't be afraid to make up information that you didn't research. Sure, if you dig enough you can find out the name of the local doctor's assistant, but it doesn't really matter much. And if you do forget to research something that turns out to be important, make it up!

Focusing on researching the bits that are likely to be important during play will help you to actually finish the research and get on with the scenario.