Fractal creates all sorts of odd maps. In one map, it was Pangaea-like, where all of the AIs were on the same continent as me, but I couldn't find good enough spots to settle three Legendary Cities, so I gave up on that map.
The map that I did play out only had me able to meet Louis and Pacal pre-Astronomy, plus technically I met Alex across of the Ocean when his Cultural Borders popped at the far end of my continent.
So, just how much interaction one gets with the AIs can vary, which is a fact that dramatically changes how the game plays out. We only had 4 Religions on our continent, three having been founded by me. By the time that I could get Galleons and conquered Cities with 2 additional Religions in them, I was unable to get Missionaries to successfully spread to any of my home continents' Cities before the game was over. So, perhaps I blundered in trying to go to war with Galleons, as there was no benefit Culturally, and the City Capture Gold that was earned probably only balanced out the cost of launching the war.
Tip: It's important to self-tech Drama for the 25% Cultural percentage earned from Pavilions (Chinese Theatres), since the AIs tend to avoid teching Drama.
I also had to delay Liberalism in order to self-tech Divine Right for my 4th Religion, netting our continent The Apostolic Palace by belatedly learning Theology on the way to Divine Right after Theology's Christianity had been founded off-continent by none other than Shaka.
Alex went to town on Hatty, declaring war 4 times on her without my interference. The one time that I witnessed Alex capturing a City, he made Peace with Hatty and then Liberated the City back to her. Alex, your tactics are bold, yet questionable.
I had trouble figuring out when to time my Golden Ages and ended up doing a lot of Civic-switching outside of Golden Ages.
It would certainly have helped to have been on the same continent as AIs who will do the Missionary-spreading on our behalf, but then there's also a greater need to defend from some of the more aggressive AIs. Sury and Alex tend to be the scarier ones, while Shaka can get an honourable mention if he gets early access to Copper.
It's also hard to predict how many Great Artists will be needed and I ended up with one too many, having worked out a way to squeeze out Great Artists from multiple Cities near the end of the game quite efficiently, only to find that my last two Cities to achieve Legendary status were going to become Legendary on the same turn as each other without the help of that final Great Artist.
I'd say that Qin is a decent Leader for this Challenge, since he has one useful Trait (Industrious), a very helpful Unique Building, and a decent Unique Unit that at least pairs well with his otherwise-throw-away Protective Trait, but his Unique Unit comes a bit late for capturing AI capitals to become Legendary Cities, especially since Machinery (for Cho-ko-nus) is not typically on a Cultural Victory's research path. I ended up using two self-founded Cities plus my capital, since I didn't feel like Chariot-rushing Pacal with his Holkans (Resourceless Spearmen) and Louis was too far away. Louis was a bit of a Wonder-hog, but at least I befriended him, so I didn't have to fight against him, even though he did take away some of the Wonders which I'd hoped to construct.
Running Pacifism with a big army was tough, but that's just a necessity, right?
As with many things in Civ 4, the sooner that you can pull them off, the less that you have to pay. The longer that a game drags on, the more that the AIs catch up and pull ahead in technological research, and the more important that having a standing army can be. That said, map layout and diplomacy both play far greater roles than having a standing army, but once I had my army built, I decided not to disband it.
