The Book of the Watchers, the core of 1 Enoch, dates to the 3rd century BCE and survives in Dead Sea Scroll fragments, the oldest extant systematic account of demons' origin. Shemihazah leads two hundred Watchers to earth; they teach sorcery, weapon-making, cosmetics, and astronomy; their giant offspring, the Nephilim, devour the world and die in violence. Their spirits, part immortal, part earthly, cannot ascend and remain as the evil spirits of the earth, 1 Enoch 7:8-12 and 15:8-12.
As the tradition retold it: the Watchers' real crime was curriculum. Azazel taught metalwork, the making of swords and ornaments; Shemyaza taught spell-cutting; Baraqijal taught astrology. Humanity's whole toolkit arrived as contraband, and every art since carries a whiff of theft.
The comparative claim: Enoch's descending knowledge-bringers parallel the Sumerian apkallu sages and, in fringe readings, Sitchin's Anunnaki, the same story of beings from above who teach, interbreed, and trigger a flood. Different archives, same incident report.
Enoch explains why demons are earthbound, why they know secrets, and why they resent us. As theories of evil go, why did the canon keep this one out?