I would like to clarify that we do understand how Ancient Egyptian mummies were embalmed. The extensive use of natron salt to draw moisture from the body allowed for long-term preservation of the corpse, somewhat similar to natural desert mummification as a result of desiccation. The bodies would then be wrapped in linen and resin and stored in sarcophagi, often underground in cool dry places, further allowing for, ahem, extended shelf life, so to speak.