"That which does not kill me makes me stronger.” ~ Nietzsche in Twilight of the Idols.
History proves Nietzsche right. The civilizations that have the resilience to withstand great catastrophes—brutal invasions, devastating epidemics, famines, civil wars, and massacres—and adapt to the new conditions generally become stronger. 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 never permanent. The side that has lost in the past might become stronger and return to the battlefield in the future, if it was not annihilated. History never ends.