Almost every pre-modern society had practices which were somewhat like hypnotism. Often a special person in a society (witchdoctor, shaman, priest...) would conduct a ceremony. The ceremony might use incantations (spells), chants, repetitive music, mind-altering substances, darkness, fire, and other settings. The purpose was to send a person or group into an altered state of mind like a trance. Even literate societies such as ancient Greece had phenomena suggestive of hypnosis. The Delphic oracle was in a trance of some kind as she uttered her famous predictions. Whether that was self-hypnosis or just the effects of volcanic gas will never be known.