After playing what I thought was a pretty strong start, I now moved into the Middle Ages and began turning my attention to the jungle in the north. Starting in jungle is of course an initial handicap in Civ4, but if you can start in a more fertile region and then expand into the jungle later on (building cottages everywhere and taking advantage of the many resources that only appear in tropical latitudes), you can often enjoy a great deal of success. I still had a few more city locations to fill in around my capital, but the theme for the next thousand years or so was going to be settling as much of the jungle as possible and making it useful. I think that the players who can do this best are probably going to have the most success in terms of the fastest finish. So on with the story! 
The first critically important event in terms of worldwide diplomacy was that Qin declared war on Kublai Khan in 200AD, with no prompting from me at all. This was fantastic news, naturally. The two dominant civs on my continent (aside from me) were going to waste their production attacking one another! Interestingly, the two civs had initially shared Kublai's Judaism as a religion, but then Hinduism spread to more of the Mongolian cities and Kublai swapped back to Hinduism. Suddenly the two were suffering religious penalties (even though Kublai had founded both religions) and their border tension must have been significant as well. What a break for me!
I had a War Chariot scouting in the area, so I decided to have him move around and watch the fun. Qin got off to a great start:
Turfan fell in 275AD, just a couple of turns into the war. (By the way, look at that minimap - if Sirian doesn't have that much land scouted out by 275AD, he will be scolded to no end!) The other reason why this is a good shot is due to the fact that it shows the city of Old Sarai as well. Qin would end up capturing this city too a little later on, after which the two sides would sign peace. So Qin gained a pair of cities on his northern border from Kublai. You never want to see a Financial civ gaining additional territory, of course, but I still was fortunate here. Qin's push against Kublai in the north meant he WASN'T pushing towards me in the east, giving me more time to settle the jungle in the north. And that was a very good thing. 
Some other things to mention... Note that I already have Open Borders with all of the civs and can trade with them all too. That means I'll have more foreign trade route income rolling in to help fuel my research. I don't plan to close off my borders ever, even though it WILL help the other civs more than it will me. Even if I get less of a benefit, I still do get a benefit myself, which will help me get an earlier launch date overall! I'm also researching Civil Service here to open up Bureaucracy, which will be a huge boost to my awesome capital of Thebes. Might as well head there sooner rather than later. Unfortunately FDR put an end to my Colossus hopes by building it himself in 300AD (extremely early for the AI!) I wonder if this will happen in every game, or if other players might have gotten ahead of me here with an easy Colossus build. (We did have copper after all, and it would have been a fairly easy wonder to build.) Oh well.
I also did note at this time that barb axemen were showing up in fairly significant numbers, although my note also reads "barb axemen slaughtered by War Chariots." It will be fun to see how everyone handles this! Some of our newer players may have a bit of a rough time if they don't get units up into the jungle to bust the fog and prevent the barbs from showing up.
By this time, several of Huayna's cities were Confucian, and I was planning a lazy push with missionaries down there to cement him more fully to my cause. Then in 375AD disaster struck and he founded Christianity! 
Gah, not good. This changed our religious relations from a +3 boost to a -4 penalty! For a little while, the religious tensions caused Huayna to close Open Borders and cut off the resource exchange we had going (I was getting silver, can't remember what I was trading away). Fortunately, I was able to reverse this by 1) giving Huayna some cheap tech when he asked for it 2) selling him a resource for some gold per turn just so I could get the "you have supplied us with resources!" relations boost, and 3) sitting in Hereditary Rule for ages on end, which is apparently Huayna's favorite civic. I eventually was up to +5 relations just from the shared civic! So we did patch things up and re-establish trading relations eventually.
Kublai Khan had asked me to join him in his war against Qin, and I had turned him down, simply because I didn't want to take sides at this point in time. My goal was to stay out of this early fight and just let the two civs beat on each other. Well... wouldn't you know it, Qin starts pushing a settler to the east around 500AD. Towards what I righly regard as MY land. I begin shadowing it with War Chariots, just to see where it's heading. The city location that Qin founded was, to put it bluntly, totally unacceptable:
What Qin doesn't realize is that the jungle north is mine. MINE! And as if that weren't bad enough, the city he founded is in a terrible location one tile off the coast, wrecking my planned dotmap up there. It must go! Thus I declare WAR on Qin on this turn in 580AD and move in to raze Hangzhou. The city is defended by an archer and a spear; my City Raider II axe kills the archer, leaving my War Chariots to face the spear. One dies attacking , naturally, but the second one kills the spear and takes the city!
(Keep in mind you can't get TOO caught up in the one-on-one unit matchups; yes, my attacking War Chariot was sure to die, but I had 4 of them on hand, so overall victory was assured.) The net effect was that I secured the entire north for myself, at the cost of making Qin a bitter enemy. Was it worth it? Of course it was! My plan is to keep expanding throughout the game anyway, and Qin has the best land that I can see for later acquisitions. (No sense in attacking Huayna, and everywhere else would be a logistical nightmare until late in the game.) In other words, I'm planning on coming back later to grab even more land. But for now, I had "staked my claim" and no Chinese settlers were going to take it away from me! (By the way, also note the other city ruins above - Qin had razed a barb city there in BC years. Much conflict in this area!)
I get peace with Qin in 760AD; the war has been phony after the initial city razing. Still, he largely backed off after this and respected my claim to the north. (A redeclaration would have followed if he hadn't!) Kublai was still the only AI civ with Alphabet at this point, by the way. There are SO slow to grab that tech! On that note, Kublai built the Great Library in 920AD. Yep, I think I could have gotten there first! 
For that matter, disallowing the Great Library when the player has marble at the start is just cruel, heh. Of course everyone will be in the same boat.
I discovered Optics around 950AD and started sending out caravels to find the other continent. Sirian's writing in his Adventure Three report aside, I *WAS* the player who won the award for scouting the most civs in Epic Two (that's Civ3's Epic Two for you newcomers!) and I plan to be the one making contact here too. 
In fact, I make contact with the other continent in 1010AD, and by conincidence meet all three of the other civs at once! (They all had units in range of the tile I saw, quite by accident.) With Frederick, I sign Open Borders and cut him a fantastic deal to boost relations: Code of Laws for Monotheism. That isn't even close to fair! But sure enough, +4 boost to relations from "fair and forthright trade". I'll take a cheap boost like that anyday. With Asoka I make a similar deal, trading Metal Casting for Horseback Riding (which I'll need if I want to build knights or cavs later on). Open Borders there too. Finally I meet Isabella, who hates me because of our religious differences and refuses to do anything. No surprise there!
Here's the map from that turn in 1010AD:
I am still at 70% research (admittedly, at a deficit) although I should be able to improve that shortly. My civ is heading down the bottom of the tree to Guilds and Banking, which will increase my revenue and put my civ in the black. Of course, as soon as I get the additional income, I will found more cities rather than increase the research rate. Expand, expand, expand! Even though a great deal has changed in Civ4, it's still better to have more cities than fewer cities. They just cost more to support. In Civ3, each additional city makes you stronger; in Civ4, additional cities give you the POTENTIAL to be stronger, so long as you can manage the costs. The best policy, if you can manage it, is to keep expanding slowly throughout the entire game, never having your finances drop catastrophically or sit at 100% science (if you're there, you can support more cities!) Of course, the other civs do get in the way of this, so it's more than just a builder's exercise.
As far as cities founded since the last screenshot, Giza and El-Amarna are more whipping colonies making use of sea resources. These towns literally get whipped every 10 turns as soon as the penalty wears off. Pi-Ramesses and Giza constantly fluctuated between about 5 and 10 population; I was a very, very hard slave-driver there! 
Slavery really is a very powerful civic, although I think few people understand just how useful it is. Aside from a Philosophical civ who would want Caste System, I really can't see too many situations where I wouldn't want to run it pre-Emancipation. As far as other cities go, Byblos fills in a gap in the north (but will soon become very strong in its own right) while Hieraconopolis and Abydos at the top of the map are just starting to get hacked out of the jungle. I continue to dominate all of the demographics, and am just generally in great shape. Qin hates me, but he'll just have to deal with it.
On a lighter note, Fred and Asoka BOTH try to trade me Alphabet on the same interturn in 1040AD. Sorry guys!
More building turns follow. I hit 10 million population in 1130AD, which is far and away the tops of any civ. I also get the circumnavigate bonus in 1140AD, proving once and for all that (at least in this game), I am not "no-Scouting Sulla". The only trade I made in these years was to get Engineering from Kublai; I don't even know what I traded him. I haven't made too many trades here because, to be honest, I'm far and away the tech leader and no one really had anything that I didn't! I suppose that's one way to deal with not having Alphabet for this game. Also on the lighter side, Fred completed Notre Dame in 1260AD. I certainly wasn't competing for that!
As a sign of my solid research, I made it to Liberalism at the fairly early date of 1320AD:
Liberalism grabs often take Economics or Nationalism, but that's not where I was going here! With no Colossus to worry about, ASTRONOMY is the tech I want. Not only is it the most expensive tech on the board, it also enables observatories for my civ. As soon as my cities finish their universities (you can see several in production right there), they will go right onto observatories, further boosting their research! Oh, and don't forget that enables trade over the ocean too (more foreign trade routes!) I will be interested to see if anyone else goes this route, as it proved to be rather effective here. Also note the size of Thebes in that shot: it's size 19! In 1320AD! And it's working no less than 10 cottages - now do you understand how I could economically afford all this expansion?
The one downside to running Slavery is that you can't run Serfdom, which I clearly could have used when clear-cutting the jungle in the north. So with marble on hand, I simply "built" myself a Serfdom civic!
I don't build Hagia Sophia often, but I actually got good use from it in this game. Thebes could build it in less than 10 turns, so it wasn't much of an investment in shields either. After discovering Liberalism, I first took a pit stop to Economics to grab the free Great Merchant (which I did get), then I began pushing up the Printing Press line of the tree towards Rifling. Why that tech? Well, rifles are pretty unstoppable against medieval units, especially if you build some maces and give them City Raider promotions, then upgrade them to rifles. And I'll have this pile of cash just sitting around from the Great Merchant, so... I think you can see where I'm going with this. 
One bizarre incident here - where did this barb galley come from? And gack, he's pillaging my nets!
El-Amarna was in the extreme south. You'd think the barb galley came from the west, but no - it came from the EAST! The only possible explanation is that it spawned literally on those two tiles of fog east of the horses. Folks, you can't make this stuff up! The minor setback to El-Amarna was almost worth it just to be able to tell this story.
Trade mission to Bombay yields 1400g in 1400AD, very nice. I also pass 500 beakers/turn for the first time in that year. (How high do you think I can get the beaker count? You might be surprised by the end of this game!) And shortly thereafter, I finish my Forbidden Palace up in the north at Hieraconopolis!
In Civ3, I was a firm believer in building an early Forbidden Palace and then riding that to an early victory. In Civ4... I think it's actually more effective to wait a little longer and build your Forbidden Palace a little further away from the palace. Certainly in games where I've built it early and close to the palace, I just haven't seen much effect. Putting it further away, like in this case, seems to provide a little bit more of a punch - although, as always, the tradeoff is that you get it later. The FP here cut about 20gpt off of my costs, which would be helpful until I could get to State Property later on (oh yes, I'm definitely going there!) The Hieraconpolis site was also well-situated for later acquisitions...
I hit 20 million people in 1480AD. And that leads us to this picture from 1500AD:
My civ is now officially out of room to expand - and isn't it wonderful that it took until 1500AD to reach that point! I still have room for two more fishing villages in the extreme south, but I'm holding off until later to found them (post-Statue of Liberty, when they will be more economically viable). All this territory and I can still run at 80% science too! Even better, I'm about to discover Rifling, and... I have an army already waiting to go. Been running Theocracy for the last dozen or so turns, training 6XP maces and cats. They just need to be upgraded now - and I have the cash on hand too. I love it when a plan comes together. (Watch out for Oxford at Thebes too, yikes!)
And just a peek at the demographics dominance:
I'm tops in GNP by a wide margin already, and my jungle cities are only just getting started. Once they mature, the AI civs will really be in trouble. I also have double the production and three times the population of the next-closest AI civ. This is already pretty close to a winning position - or at the very least, I'd need to screw up royally to lose this one. I have no plans on losing, however - I'm about to requisition myself some more land at Qin's expense. Wait 'til you see what I have incoming into his lands!
