Sethians? Never heard.
Please Slim be yourself. Im not learned to see "one sentence SlimJim."
EDIT: Okay. I found it.
Sorry the L I was being summoned to watch football. It aint an easy topic to find good sources on either.
The Apocalypse of Moses (literally, the Revelation of Moses) is the usual name for the Greek version of the Life of Adam and Eve. This title was given to it by Tischendorf, its first editor, and taken up by others. In the text, Moses is referred to only in the first sentence as the prophet to whom the story was revealed. The Greek Apocalypse of Moses (not to be confused with the Assumption of Moses) is usually considered to predate the Latin Life of Adam and Eve.
After being banished from the Garden of Eden, Adam and Eve go to the East and live there for eighteen years and two months. Eve gives birth to Cain and Abel. Eve dreams that Cain drinks the blood of Abel, but that it then came out of his mouth. Cain kills Abel. Michael promises to Adam a new son, and Seth is born in place of Abel. (chapters 1-4)
Adam begets 30 other sons and 30 daughters. As Adam falls sick and is in pain, all his sons and daughters came to him, and he briefly recounts to them the story of the Fall. Seth and Eve travel to the doors of the Garden to beg for some oil of the tree of mercy (i.e. the Tree of Life). On the way Seth is attacked and bitten by a wild beast, which goes away when ordered by Seth. Michael refuses to give them the oil at that time, but promises to give it at the end of time, when all flesh will be raised up, the delights of paradise will be given to the holy people and God will be in their midst.
Seth is also mentioned in the context of Sons of God and Sons of Seth compared to the Daughters of Men and Daughters of Cain. This is tied in with the Watchers and Nephilim. Some do think that the Watchers are reminiscent of shamans because they are often depicted anthropomorphically. They were also described as the teachers of various practices that shamans would have been likely to know.
We don't need to think in terms of aliens, angels and giants because Cain is the farmer and Abel was the sheperd. What does this make the third son Seth then I wonder. Remember Adam had thirty other sons and daughters so what is special about Seth. I would say he blessed for some reason and is connected with the oil. Thus I conclude he was given knowledge of shamanic mysteries and this is how the lifestyyle of hunter-gatherers in the form of shepperding survived i.e. because they discoverd more from the wilderness of value than just livestock. Some of the most precious products may have grown wild.
Another story of conflict between agriculturalists and shepperds is Set and Osiris. Osiris is the farmer and god of the earth and Set is linked with the wilderness. In this instance Set was the victor because it relates to climate change most likley. In a drought the farmers would die first, they were also most at risk from plagues of rats or locusts. Hunter-gatherers on the other hand may be wise enough to ride out such catastropehs by moving to coastal or forested regions for food.
Just to clarify I am taking the stories as alleorical more than literal and describe broad groups of people and their cultures more than indiivduals.
Sethian Chritians were gnostics and used plants for medicinal and psychedelic reasons. They were big on spiritual purity but were rejected by the Cathollic Chruch quite early on.