It's geo-political conflct amongst China, India, and Pakistan.
The region is the source or headwaters to rivers of major interest to the Chi-coms, the Pakistanis, and India.
It's also a religious and ethnic conflict. Indian PM Modi has been deconstructing Kasmir's regional identity to further integrate it with the rest of India. New laws have taken away historic autonomy for the region and allowed outsiders to settle in the region.
We can thank the British for this mess. The Raj was a collection of smaller principalities under British control or "protection". In 1947, each principality had to decide to join Pakistan or India. The fate of Kashmir, as a semi-autonmous, principality in the Raj was not settled before the British withdrew from India. Pakistan occupies part; India occupies part; China claims or annexed parts as well.
Modi is a Hindi ultra-nationalist who has also been ruffling ethnic feathers with similar policies in Assam, which is also of interest for China as source of irrigation water.