In the Tibetan Book of the Dead, Bardo Thödol describes the 49-day period between a person's death and rebirth.
Vajrayana [Tantric] Buddhism, which originated in Central Asia and particularly in Tibet, developed the concept of bardos, the intermediate or transitional states that mark an individual's life from birth to death and rebirth. The period between death and rebirth lasts 49 days and includes three bardos.
The first is the moment of death itself. The consciousness of the newly deceased becomes aware and accepts the fact that it has recently died and reflects on its past life. In the second bardo it encounters frightening apparitions. Without understanding that these apparitions are unreal, the consciousness becomes confused and, depending on its karma, may be drawn into a rebirth that impedes its liberation. The third bardo is the transition to a new body.Bardo deities appear to the deceased for forty-nine days while the deceased is in the bardo. First the peaceful deities appear, and if one does not recognise and become liberated through the peaceful deities, then the wrathful deities manifest. If the deceased has not been able to connect with the deities during this forty-nine day period, then the consciousness is pulled back into rebirth within the six realms.The Deities appear to the deceased during their time in the Bardo. There are forty-two peaceful and fifty-eight wrathful Bardo deities. The image above shows a wrathful Bardo deity with a crow's head.