Apparently PRC has always kept up its knowhow in different armament fields.
mig23/27 from Egypt, probably also sukhoi 22, mig 29, F-16; Mirage III, V, F-1 by Pakistan; F-14, phoenix, harpoon, hot and hellfire from Iran; ... leo1, Leo2, amx30, M-1, chieftain etc. either whole weaponsystem as a gift or acces to subsystems in exchange for hard cash or military hardware.
Lord knows what hidden beauties we are as yet to encounter.
The PRC was clearly following closely but lacked state of the art production facilties.
The fact that they didn't produce any 'modern' weaponry in the 80's wa mistaken for a lack of knowledge.
This explains rapid catch-up and fast production rates of modern weaponry as those facilities (and budget) eventually came at hand after a long period of austerity and stimulating and modernizing of industry.
In mind and on the board these systems already existed!