You egyptians they constituted an extremely religious society. That religiosity determined cultural and social practices among the Egyptians - one of them was the belief in immortality. For the Egyptians, death would be fleeting and life would return to the body, but the return to life would only happen if the dying person's body was preserved.
If the soul (Ra) did not return to the body (Ká), it meant that the body had not been preserved. Hence, the importance of body mummification, embalming and preserving to prevent decomposition. For this, there were advanced mummification techniques for the nobles and simpler techniques for the poor.
The advanced mummification techniques developed in Ancient Egypt only existed because of the developed medicine. You egyptian doctors they performed surgeries, cared for fractures, knew human anatomy. In addition to the technique of preserving bodies through mummification, the Egyptians needed to develop a method of protecting bodies against looters, hence the construction of huge tombs.
The tombs would guarantee the conservation of the bodies. Usually when a rich person (Pharaoh), who displayed power, died, his body was mummified and later placed in the tombs that were considered a real dwelling. In them, the pharaoh and his riches were buried in a royal chamber and his servants (employees), scribes, priests and animals in other, simpler chambers.
The sacrifice of other people at the death of the pharaoh was explained by the belief in immortality - the return to life it would mean having other people to serve him (the servants) and continuing his wealth was fundamental to exercising the power.
It should be noted that the belief in the return to life took place among all social strata in Egypt, but the pharaohs, nobles and rich were able to build well-sealed sarcophagi and large tombs built from stones. All this ensured the protection of the bodies against looters.
The main tombs were the mastabas (tomb made with a stone or brick slab), the hypogeum (tomb made in the rock, near the banks of the Nile River) and the pyramids (Royal tombs consisting of a crypt, ventilation corridors, the king's chamber, secret corridors, galleries, chambers and false passages in order to prevent looting).
Leandro Carvalho
Master in History
Source: Brazil School - https://brasilescola.uol.com.br/historiag/morte-mumificacao-no-egito-antigo.htm