We (Umarth, Jet, Legendre and me) are currently playing a Mongolian Monarch AP victory game (succeeding, I might say). If anybody has any other AP victories please post some screenies. (Doesn't have to be 600 AD start)
What, no takers?
Actually AP victory is very hard (diplo victory in a large map such as RFC is hard in general). The problem with the 600 AD start is that so much of the world pop is Christian, and any of the other civs (Spain, England, Russia, America) will easily destroy any lead you might have.
An easier goal might be with China or India building the AP with a non-Christian religion, and maintaining isolation until free religion so that no negative diplomacy will occur until the time for mass conversion comes.
I just tried it out in vanilla, since I've never even done it with that. Getting the vote even after you've spread to every civ is trickier than I'd've imagined. I hope we don't have that problem in the Mongolia game.
I managed AP victory with Arabia. Conquered Aksum early converted state religion to Christianity, got voted into the palace. Then went about conquering India and Central Asia. Arabia's advantages in a 600AD game made it easy to get the AP victory by 1706. I did have a bit of luck though with Turkey vassalizing to me. That was unexpected . I'm presently trying India, got stuck with Spain and England, but I managed to use an exploit I figured out. Settle a city and spread your desired religion to it, the city should ideally be in that civ's historic sphere, then gift it to them. That's how I got Spain and England Buddhism. I'm doing AP with Buddhism. I'll need 399 votes out of 500 and my vote share alone is 200. It won't be easy though.