Ming the Merciless is an alien, and as such he should have no particular connection to any Earth culture, but of course that's not the way science fiction traditionally works. As his name implies, Ming has elements of Chinese culture, or rather of early 20th Century Western stereotypes of Chinese culture. With his ornate high-collared robes, droopy mustache and long goatee, Ming the Merciless is the very epitome of a "yellow peril" villain. Sax Rohmer's character Fu Manchu is the first and most famous of these racist depictions, and Ming is his direct descendent.
Lacking any real knowledge of Asian cultures, Brits and Americans feared the manipulations of "inscrutable" Asian masterminds, pushing drugs and building criminal empires across the world. Ming was that same idea translated for a sci-fi context: an invading alien dictator posing a threat to the white heroes and their women. Basically, it's a very bad look.
Inevitably, Ming was always played by white actors, which doesn't help. Charles Middleton in the cliffhanger series wore makeup to look more Asian, in the racist Hollywood practice commonly referred to as yellowface. Max von Sydow in the 1980 movie wasn't made up that way, but he still wore the Asian-inspired robes and facial hair. As time passes, Ming increasingly becomes a major problem for the Flash Gordon property. He's widely known as Flash's main arch-enemy, but every trait associated with him seems increasingly problematic.
