Note they cost a shit tone each as well they have other lower level Rocket and like S400 Russian missile system… most of which are kinda left over from Russia help so on in some way. China has actually neglected to sell them any rocket systems in this aspect I believe it is due to Afghanistan’s proximity to their own country being a boarder country to China itself on the back sides.
The land mass allows for a warning time between countries more and not that China could not builds something but as far as I know they do not have anything operational even ready with in the area. The other S400 do not have the best aim is the thing so it is largely not feared in this way.
So the reality is that Russia is to far away really for the S400 which is why it was sold to them in this aspect as it posed little to no threat to Russia in itself so on.
This this is the kinda information that is done in some ones head that understands the limitation of missiles range speed and effectiveness. You obviously did not read or know much of anything in this aspect or way. What are claiming to have gone to war game collage and got an “F” but magically passed and became NASA top rocket researcher?
So again…
Who the bell are you…?