Basically its the entire Eastern Hemisphere Map: Roughly this: http://www.ict.griffith.edu.au/wisem...Eurasia116.gif although a bit more southerly to offer a bit more of west and central africa.
Roughly 1100 start. Makes IMO good use of the seven culture limit and the 30 factions to really give you access to a pretty in depth European-Middle Eastern and Indian-Oriental Theaters of War with access to the Steppe peoples and Sub Saharan Africa for a bit of flavor. Kievan Rus and Novgorod are lumped with Europe Culturally but would have equal similarities to the Steppe peoples and so would Hungary and Poland to a similar extent.
Basically rather than attempting to focus on an Area and make every faction playable I thought it would be better to pick the empires with greater potential for dominance.
Religions would be: Catholicism, Orthodoxy, Paganism, Shintoism, Hinduism, Buddhism, Itanism (African Paganism), Shamanism (Mongols), Islam, and Heresy. Those seem like big enough categories to adequately do conceivable conflicts.
Im not sure on the faction names since many places tended to change hands a lot so I'm open to ideas of course. As it spans from Britain to Japan and lots of the regions are huge there would be permanent stone forts to fill in the lesser cities. Venice and Milan were dropped because they strike me as minor duchies floating between Germany and Rome. Sicily has better options with it's control of the central Mediterranean. I also felt Denmark was basically just a small kingdom north of the Reich. Norway however had potential to dominate the North Atlantic and Sweden the Baltic and I thought that was more interesting.