The Book of Traversing Eternity
An ancient funerary text that is said to describe the experience of the afterlife. More specifically, it is believed to include instructions for how a soul may freely navigate and traverse the various planes of the afterlife. In addition, there is an entire chapter devoted to the depiction and description of various rituals that may be performed to help the spirit of an individual become preserved in the afterlife, as well as a separate chapter for rites that may help ease an Unsent spirit into their fated afterlife.
Based on the language used in this text, historians assume that many of the practices described within were only intended to be performed on regents (and possibly their family).