I agree with asenathwaite. Industrial revolution would likely be your best bet. My reasoning would be the mass use of iron, even if it is a little cliched. Another thing that you might try would be fire arms. They didn't become that widely used until around the 15th or 16th century. Something about the chemical make up of black powder perhaps? Even once we stopped using black powder, by that point, most of the "civilized" world would have stopped believing in things like magic and most magical theory suggests that beleife plays a large role in magic. That's of course, if this world that you have created is based off any sort of magical theory. *shrugs* Hope that helps give you idea. ^_^