I have one savefile that has each neighborhood and world set in a different time period; exploring the past of my vampires.
These time periods include the viking age (on the island in windenburg), the golden age of piracy (in sulani... princess cordelia is also there), the 70s (in newcrest), and the early 2000s (willow creek). I also consider adding the regency era for a fifth vampire somewhere, but we'll see.
I use CC for most of this, but what's hardest to come by is the viking stuff. I've only found properly accurate viking tunics for TS2, and I've come to the point where I'm trying to figure out how to make CC clothes so I can do this myself. Nobody ever does viking content for TS4, it's all celtic instead. Which I guess is close, but really not what I'm looking for!!
So in an official context it does feel incredibly unlikely for them to provide anything for iron-age scandinavian sims, since that's just in my part of the world anyway. It feels too specific. Come to think of it, they haven't really done any specifically Scandinavian stuff since TS3 with Aurora Skies.
So I may just settle for plain medieval stuff if they decide to provide anything for historical gameplay. Which is also very unlikely, knowing how deeply rooted TS4 is in specifically modern-day gameplay. I mean heck, I had to get a mod to keep everyone from playing on their phones all the time. Phones, which people are just born with.