Japanese didnt know popcorn until America built bases there...
I'm pretty sure it's the same with the Germans. In the mid-sixties, popcorn vendors over there were selling "Iowa popcorn." Interestingly, they called it "popcorn" and not the German term "Sprengmais" (exploding corn) and "Iowa" probably reassured the Germans that it was not German corn, which is used to feed pigs.