Very funny jokeThere is no proof for insecure hindu but enough proof for rest of the world. Sanskrit was developed in ancient Pakistan, and the reason is they migrated from sttepe in to ancient Pakistan. You don't believe that central/peninsular Indians migrated to ancient Pakistan just to develop sanskrit right?
The earliest written languages of ancient India were Prakrit and Sanskrit of eastern India and Tamil of southern India.
The earliest Prakrit and Sanskrit inscriptions were made by the eastern Indian Maurya Empire and the Satavahana Dynasty of Peninsular India. The Pakistani people merely copied the Brahmi script of the eastern Indian Maurya Empire.
There are more Greek and Persian inscriptions in Pakistan than Sanskrit records because Pakistan was mostly under the rule of foreigners like Greeks and Persians.