It is difficult to identify when in history dying at holy spots, usually by a holy river like the Ganga, became associated with achieving Moksha, which itself has more than one meaning. The most common understanding is that it means liberation from metempsychosis or the endless cycle of birth and rebirth, but others believe that dying at places like Prayagraj (earlier called Allahabad), and Kashi could mean a good rebirth as a richer, more powerful person. There's the hope that either you can escape rebirth or at least be born in better circumstances next time. Since it all happens after one's death, we don't know more. The earliest historical reference to people dying by suicide at the Sangam or confluence of the Yamuna and Ganga is present in Chinese traveller and Buddhist monk Xuanzang's record of his visit to Kannauj where he was a guest at King Harshvardhan's court for nearly two months. During this time, he attended a great Magh festival where Harshvardhan and other kings distributed massive amounts of wealth to ascetics