The Book of the Dead, also known as the "Black Book", was an ancient Egyptian book that can bring dead people back to life and a prominent object featured in both The Mummy and The Mummy Returns.
The Book of the Dead contained ancient spells and incantations that can resurrect the dead and summon the Warriors of the Book (Ghost Warriors).
In the late 3000's BC King Ramusan protected the Black Book of the Dead in the treasure chamber in his palace to keep it safe from anyone. Years later, Imhotep took the Book of the Dead from it's holy resting place so that he can perform a ritual so that he can resurrect his love interest, Anck-Su-Namun back from the dead but was caught and was arrested by the Medjai who followed him and his priest minions and then Anck-Su-Namun's soul was sent back to the dark underworld. And the Black Book was sealed away inside a cursed canopic chest in a compartment underneath the Statue of Anubis along with the five sacred canopic jars that has Anck-Su-Namun's organs.