After like 7 sessions, I'm still fighting with this one. Almost constant war since Monty DOW'd on me around turn 50. Had a lenghty war with him first with chariot archers and warriors, but only managed to capture his first city after I got Keshiks via liberty finisher GS and upgrading my chariots. Even then it wasn't easy as the terrain is tough. What made it even harder was the fact that he had the Great Wall and spammed only pikemen. But when I capture the first city, taking the second one wasn't that hard. Just as I was about to finish him my taking his 3rd and final city, Siam DOW'd, so I got a peace treaty with Monty and step by step captured quite a few of Siam's cities.
Currently at 1888AD Monty is still alive with 2 cities, one cutting my empire in half, but I don't mind. I think there is a strange bug going on, as Monty has about 25 pikemen scattered all over the place and even embarked near his cities. He has had -35 GPT for almost the whole game, and he has done practically nothing. Only recently he just DOW'd Siam. I had peace with Siam for a while, but as he was still tech leader and otherwise pretty strong after I'd taken some of his cities, he had a strong army at my border, preventing me from continuing my conquest. During the game other AI's had beaten some of my competition, so only Russia and Songhai remain in possession of their capitals.
My invasion army consisting of Mech inf, artillery, battle ships, carriers with fighters and most importantly hugely experienced Keshiks (!) has started moving towards Catherine, who DOW'd me after I DOW'd Siam, even when they were at war with each other and I had really friendly relations with Cathy. I had prepared to invade Cathy earlier by capturing Stockholm, so I had had a nice beachhead close to Moscow to start the invasion from, but Cathy took it from me as I had no proper defences there. The Keshiks are awesome, even when I have lost a Keshik from time to time, one of them is close to reaching level 10. Warfare is really slow with them, as micromanagement (with road building) is really important with them, but they can seriously hurt even mech infantry without even being damaged themselves! This type of warfare has lead to a situation where I'm not taking full advantage of the Khans, but that's a sacrifice I've had to live with.
I'm usually not a warmongerer, so this game has been a learning experience, and I think I should be able to reach domination victory at a late date. Still can't understand these players who reach it even before 1800AD, especially with some AI's on different continents.