Meng Po is the Lady of Forgetfulness in Chinese mythology.
Literally means Old Lady Meng, Meng Po serves in Di Yu, the Chinese realm of the dead. It is her task to ensure that souls who are ready to be reincarnated do not remember their previous life or their time in hell.
To this end she collects herbs from various earthly ponds and streams to make her Five Flavored Tea of Forgetfulness. This is given to each soul to drink before they leave Di Yu. The brew induces instant and permanent amnesia, and all memory of other lives is lost.
Having been purged of all previous sins and knowledge, the dead spirit is sent to be reborn in a new earthly incarnation, and the cycle begins again.
Occasionally people are able to avoid drinking the brew, resulting in past life memories surfacing in children.