how good is AI at domination?

Playing on emperor I have never seen a runaway conqueror, someone that took time to reach you and you desperately defend against until you flee to Alpha Centauri. AIs tend to resist quite well to warmongers, I never see one gobbling more than 1 neighbour. Is that something that can happen, to be the last on the list? Or is the AI only good at competing for the other 3 victories?

 

I had a game where Mongolia took like 50 cities, including every single city state, leaving only me and Egypt (who conquered other civs land and capitals, but lost his own) remaining. What was funny was my tourism dominated Mongolia, but not Egypt, and Egypt's tourism dominated Mongolia but not me. So when Genghis took Egypt's last city, I won the next turn.

But usually if an AI does well militarily, they get ahead in culture or science too and win by another method. War was still a big part of their winning, even if it wasn't what formally gave them their trophy. This can be true to humans too.