Tib., bar-do'i thos-grol, pronounced as Bardo Thötröl
According to tradition, a sacred text based on oral teachings by Padmasambhava and recorded in written form sometime around the year 760. After having been hidden as a so-called terma, the text was then rediscovered (and extended) by the terton Karma Lingpa in the 14th century.
The text is part of the Kargling Zhikhro collection of the Dzogchen tradition and shows traces of earlier and originally pre-buddhist Tibetan thought; indicated by symbolism and divinities that are part of the shamanic Bön religion.
By way of the early misrepresentation of the text by Evans-Wentz (1878-1957), the Western reader has come to know this text as The Tibetan Book of the Dead, a translation that has misguided many readers. A much better translation is Liberation by Hearing During One's Existence in the Bardo.
The text is usually read aloud (i.e. "liberation by hearing") to someone in bardo, sometimes as pure instruction for meditation and, at the time of death, to prepare the mind for the adventures ahead.
Evans-Wentz, W. Y. The Tibetan Book of the Dead. London: 1927. New York: Oxford University
Press, 1927. Reprint 1960.
Fremantle, Francesca, and Chögyam Trungpa. The Tibetan Book of the Dead: The Great Liberation Through Hearing in the Bardo. Boston and London: Shambhala, 1975.
Lauf, D. I. Secret Doctrines of the Tibetan Books of the Dead. Boston and London: Shambhala, 1977.
Reynolds, John Myrdhin. Self-Liberation Through Seeing with Naked Awareness (Tib., Rig-pa ngo-sprod gcer-mthong rang-grol). Barrytown, NY: Station Hill, 1989.
Thurman, Robert A. F. (trans.). The Tibetan Book of the Dead. New York: Bantam, 1994.