The Egyptian afterworld: a twelve-hour night journey through gates, caverns, and guardians, which the dead king, and later anyone with the right spells, had to survive to rise with the sun.
Documented
The guidebook tradition is carved in stone
Documented: the Amduat appears in the tomb of Thutmose I (c. 1500 BC) and covers the walls of New Kingdom royal tombs, hour by hour: twelve regions of night, the sun god's barque, the serpent Apep's ambush, the resurrection at dawn. The Book of the Dead (Book of Going Forth by Day) put the same technology in papyrus for non-royals: Spell 125's judgment, named gatekeepers, the negative confession. Erik Hornung's surveys of the afterlife books established the modern reading: the Duat is less a place than a process, regeneration narrated as geography.
Assessment: Fully documented texts, on walls and papyri, translated and catalogued. What they describe is unverifiable by construction; what they document about Egyptian thought is precise.
Stories
Hell, with better paperwork
The popular version files the Duat as the Egyptian hell: fire lakes, knives, demons with names like Swallower of Shadows. The folk reading is not wrong about the furniture, the fire and the knives are in the texts, but it misses the direction. Most of that violence is aimed at the damned and the sun's enemies, and the prepared dead sail past it. The Duat's terrors are a border crossing, not a sentence.
Assessment: Documented as a widespread misreading, corrected by the texts themselves. The Egyptian fear was not torture, it was erasure, and the torture chambers were for other people.
Interesting claims
The Duat as a map of somewhere else
The interesting claims: the Duat is a star map, its hours corresponding to decans and the underworld Nile mirroring the Milky Way; or it is a memory of altered-state journeys, the guidebooks describing what initiates saw; or, in the ancient-astronaut shelf, a technical manual mistranslated as religion. Bauval and others have proposed Duat alignments at Giza, the sky made ground.
Assessment: The decan astronomy is documented and real, Egyptian afterlife books are saturated with stars. The leap from starlit symbolism to star map, or to machinery, is the interpreter's, not the Egyptians'. File the sky-reading as plausible symbolism, the rest as ambition.
Sources and further reading
The Amduat, tomb of Thutmose I onward (c. 1500 BC), the twelve hours
Book of the Dead (Book of Going Forth by Day), papyri incl. Ani, c. 1250 BC
Book of Gates, royal tombs, the gatekeeper catalogues
Hornung, The Ancient Egyptian Books of the Afterlife (1999), the standard survey
Faulkner, The Ancient Egyptian Book of the Dead (translation, 1972)
Worth asking
A civilization that maps death as carefully as its own geography is either wrong about everything after it, or we are missing a file.