There are ruins, scattered about the world, and all are sealed with unbreakable locks.
When all of these locks suddenly open, what emerges?
A cave with weapons sunken into the walls, blades sticking out of the floor and ceiling, and so on. Possibly, any weapon used in it could be torn out of the hand and sink into the stone.
A nation was conquered and the conquerers took control and put themselves in all positions of authority. One major problem, the new rulers and the now peasant/ruled class speak entirely different languages.