The earliest known account of a near-death experience from an actual documentary source (as opposed to a religious or mythological one) comes from ancient China - around 2,600 years ago.
It forms part of a slightly later account, both of which are concerned with validating prophecies received in the other world. This had political motivations as well as spiritual ones - though both were grounded in proving the reality of the NDE.
These two accounts are included in October's Historical NDE of the Month - exclusive for all Patrons on my Patreon page. New to Patreon? Click here to sign up or learn more.