There is much the ancient world can still teach us, and one of the key lessons today is that mass migration – motivated by war, societal collapse, and poverty – is capable of destroying even the mightiest of empires.

At the height of its power, the Roman Empire was so vast and omnipotent that it was run on the basis of the dictum: “Roma locuta est. Causa finita est” (Rome has spoken. The cause has finished).