The empire that dominates most of the then known world after this is the Roman Empire. It is represented by the legs of iron. This empire is hard like iron, rigid and strong and it lasts for hundreds of years exercising great power. When the Roman Empire disappears in the fifth century AD, there will no longer be an empire after it that alone dominates most of the world.
40 And there shall be a fourth kingdom, strong as iron, because iron breaks to pieces and shatters all things. And like iron that crushes, it shall break and crush all these.