I think they're just trying to "cover all the bases" with a new line.
Which to someone who knows the difference and cares means they're really not satisfying anyone.
The dragon theme must be selling well as its still around. Yet any historical sets were gone after a year or so (Romans, Egyptians, prehistoric). Yes, I know all the things they did wrong - like no opponents for the Romans and Egyptians.
Maybe the Asians are to be opponents for the dragon knights?