Medieval is a standalone game, it is not part of Sims 3. Medieval does have it's own expansion though, the Pirates & Nobles EP.
MedievalMods and Sims3mods: Dive Cave Reset Fix, Resort Revamp, Industrial Oven Revamp, Will O' Wisp fix, UI Sounds Disabled, No Cars, Gnome Family Planner, Townies Out on the Town, No Martial Arts Clothes, Fast Skilling, etc.
http://simsasylum.com/tfm/