Basically it was a giant stew of small states of various religions, cultures and beliefs. Then everything changed when the English showed up. After the second world war, and the English were divesting their empire like a used coffee filter, the place was partitioned into its modern borders with the Islamics supposed to be in Pakistan while the Hindus and other assorted were supposed to be in India. Of course this required mass migrations of people which didn’t exactly go off without a hitch and so old grudges from before the British colonial days bubbles back up and there were a couple of casual genocides.

So now you’ve got enclaves in both countries, historic grudges and now (in the 1950s) you’re one of the many fronts in the Cold War.

That evolves into a shooting war every once in a while between the two countries with the Indians also squaring off against the Communist Chinese from time to time. The Chinese are still interested in keeping things going because if they can team up with one side, they get a good access to the Indian ocean.