My attack on Portugual started badly, I took Lagos, but 2 swordsmen had died to Henry's spears, even after my cats took a hit point off. I had just finished researching Feudalism and had MI in production. After taking another city w/losses, my forces were spread too thin. I couldn't get enough defense to my iron city and Henry captured it and another city.... and I still didn't have a boat in the water. It was looking like I might take a loss as barbs were harrassing my workers trying to connect the horses. But my 4-5 MI and a few cats turned the tide, and in a couple of turns I had my iron back. I kept advancing and taking cities while still cleaning out barbs, and finally managed to make a couple of galleys.
Around 250 AD, I was researching invention when I contacted Korea, I gifted them up to the MA and traded for monotheism and soon started making contact with other civs, trading tech for any money the ai had. I was still losing quite a few units to weak spears, But finally conquered Portuaul around 750AD.
By 1000AD, I had 33 cities, but the long war with Henry had wiped out my desire for conquest. I had built Copernicus' Observatory, and had achieved 4-turn research going for chemistry, right after making a 4-turn detour for music theory(I couldn't wait for the ai to build harbors and I needed the happiness). I had decided to try for the Diplo victory and the few conquistadors I had made never saw action. Eight turns form entering the IA, I had completed JS Bach's and started my GA in 1170AD, saving a lot of money by turning down the science slider. I gifted all the other civs up to the MA as well, so they could make more money, and sold tech to them whenever they had gpt, luxuries or money to spare. Research went smoothly, and I estimated I could do well in the IA as well. I had quite a bit of culture on the border with France as well as most of my army to keep them in check. I entered the IA in 1240AD.
Korea didn't get off their island, but every few turns they had more gpt, gold, and a few optional techs to trade as well. I like Korea in my games, since they always have money, and to trade for tech when entering a new age. Monotheism would have been my next research after invention, and they saved me 7-8 turns with that trade. I'm not sure what their extra bonus was, but even after taking all their gpt they still had some tech to trade-chivalry, printing press, democracy, etc. and were a big contributor to my treasury.
So, have you done in your rivals and finished the game here, or do you plan to make them suffer for a while longer. 
Also, how did the Koreans do in your game; since they were isolated they started out with some additional help - did they play any significant role in your game?
