Its not that strange, some manufactures only export what they manufacture or they have two lines one for export and the other for domestic sales. It is only the brand names that are not in china, the frames and engines are likely plying around tracks in china someplace?


Those are aluminum frames and likely there is one or more sources that are making them, its big country.
All the engines in the three bikes you listed are different, the first is a air cooled and less then 249cc, the second is the Zongshen 249cc water cooled SOHC 4-valve and is the engine Asia wing also has in some of the marketing images I have seen of their 250 motocross model.