I have had the pleasure of reading books from authors such as Terence McKenna and Richard Strassman MD.. including The Archaic Revival, DMT: The Spirit Molecule and more.
I'll just drop in a few articles from Wikipedia and maybe a video or two and get this started...
"Many New Age spiritual seekers travel to Peru to work with ayahuasqueros, shamans who engage in the ritual use of ayahuasca, a psychedelic tea which has been documented to cure everything from depression to addiction. When taking ayahuasca, participants frequently report meeting spirits and receiving divine revelations. Shamanistic techniques have also been used in New Age therapies which use enactment and association with other realities as an intervention"
Article on psychonautics:
DMT: The Spirit Molecule (the movie):
sry about the video flood but one more on holotropic breathwork: https://www.youtube.com/watch?v=qCzG9QsM-Pw