With that said here are the type of drums
Korean (they are a hit or miss, alot of people have had problems with them) You can tell by the small spot welds. like in the pic.
Chinese (not imported anymore) They have a 36 inside a triangle among other markings. They even come in a 100rd drum.
They even have a 9396 inside a circle
"Bulgy" (from what I've read a person got a stock of chinese drums and rebranded them with arsenal markings and tried to import them from bulgaria but in reality they were just rebranded chinese drums)
Romanian( best price on back loading drums, unless you're going for collector value) It will say, "made in Romania" in the winding key.
Romanian top loader( from what I can tell, they don't have any markings)
Russian top loaders look exactly like the Romanian top loaders but they might actually have Russian markings, I'm not sure. (also rare)