-Jamaica (What I would do for a Jamaica wank)
-Haiti (Let the first black republic stand up the colonial powers)
-Dominican Republic (Ok now thats just nationalism kicking in but still)
-Vietnam (Everyone loses against Vietnam, by that logic it should be a huge empire)
-Tibet (eat your heart out, Papal states)
-Venice
-Ireland (Why can't Ireland conquer Britain
just once)
Late Western Roman empire (I'm talking post 430 AD. Let some pull of An Age of Miracles type situation instead of letting it die)
-Ethiopia
-Ghana
-The Philippines (especially The Philippines)
-Romania (Even if just a vampire wank)
-Templar wank (Highly trained corporate mercenaries in the middle ages, the story writes itself)
-Mexico (especially if it manages to beat the US somehow)
-Korea
-Something Piratey like state the others have mentioned
-Ancient Israel would be interesting for once
-SOMALIA

(bonus points if its a Somalian pirate wank too)
-Crusader states
-Latin Empire
-Iroquois