Eesfet Oon-m'Aa Poo is an Isu vault located along the Nile in Egypt, underneath the Great Sphinx of Giza. This vault remained hidden until some time in 48 BCE, when the Medjay Bayek of Siwa visited all of Egypt's Stone Circles and in turn triggered its appearance.
Within the vault, Bayek activated a pedestal and witnessed a recording made by the Sphinx messenger. Dated one hundred and nine days after the Great Catastrophe, the message displayed was intended for Layla Hassan, who was reliving Bayek's genetic memories in 2017. Accompanying this, Bayek received an ancient outfit.
- Eesfet Oon-m'Aa Poo is a romanised version of the Egyptian "(Isft) (wn-mAa) (pw)". It roughly means "Falsehood, Reality, whichever / it doesn't matter", and is a loose translation of half of the Creed's central maxim, "Nothing is true".