I seem to remember there being a sourcebook for the vampire counts that detailed their lands and had adventures for that region and such, maybe even a campaign. I think it was for WFRP 2e, but I'm not completely sure.
I'd love to run something like this in WVRP 4e.
Does anyone know what book(s) for this, please?
Well, there was "Night's Dark Masters" about the Vampire clans for WHFRP2. The pdf should still be available on DTRPG.
"The Thousand Thrones" campaign, also for WHFRP2, is concerned with some Vampire prophecies, among other things, and one of the adventures is set in Sylvania.
Hope this helps!