The True Name -also called Ren- of a mummy is a vital part of its existence, as it describes the platonic existence of the mummy. Anything that affects the True Name affects the mummy in turn. Every person, even animals and objects, have True Names that can be affected by those who know how to use it and this is one of the reasons mummies are especially cautious who knows their True Name.
The lore of True Names is explained within the Ren-Hekau path.