That's a very good point!! In saying that though, you could also throw the likes of Rome, Persia, Mongolia and many others into that category as they all at one stage ruled the 'known World' (what was known to them at least). If we take into account the game ending after all other Civs have been dominated then one of the ancient Civs would definitely have won a long time ago. You could probably say the same for science and culture victories. It's a lot harder to apply these rules to modern societies and opinions have been divided on this forum because everybody has a different take on domination/cultural/science/time/diplomatic victories.