"That which does not kill me makes me stronger.” ~ Nietzsche in Twilight of the Idols.
History proves Nietzsche right. The civilizations which possess the inner strength to withstand great catastrophes—brutal invasions, devastating epidemics, famines, civil wars, and massacres—and adapt to the new conditions often become stronger over a period of time. No civilization can dominate the world forever, because other civilizations, which might be down today, are learning and adapting, they are trying to become stronger, they are trying to develop new strategies for capturing the territory and wealth of their rivals.
Victory is not permanent. The side that has lost in the past might regain its strength and return to the battlefield to settle old scores and make new conquests. History never ends.