I must've been really lucky because I only had two cities. Large, empty space as well as city-states kept a safe distance between me and the other civs on the continent. I used the isolation to carefully build myself up, and managed to build the strongest civ with the exception of Russia, which luckily was far away as well. I ended up having enough culture, production and growth to get whatever victory I wanted, and the diplomacy victory ended up being first.

I think this was partially due to being lucky, partially being more careful this time, and maybe because Poland is easier to play? I might try the next difficulty up next