Initially China said 370 was an internal affair but last month end they decalared it unlawful & void

China calls division of J&K unlawful, India says our internal matter | Nov 01 2019

What exactly got China riled up ?

Since 370 we allowed allowed foreign delegations to visit the Tibetans in Dharamshala

We've allowed the US ambassador to visit Tawang

We seem to be getting closer to the Taiwanese

That's three things that got the Chinese

It is interesting that all these three events took place around the time of the M-puram visit or Xi's return visit for Wuhan