Full mummification of the elaborate classical kind was never universal across Egyptian society at any period. It began as a royal and elite privilege in the Old Kingdom and gradually extended, over the following centuries, to a wider though still comparatively wealthy stratum of Egyptian society able to afford the specialist labour, materials and burial goods the process required, while poorer Egyptians throughout Egyptian history continued to be buried more simply, sometimes still achieving natural preservation through hot dry desert sand alone rather than through deliberate embalming.
Mummification reached its most technically developed form during the New Kingdom and continued, with variations in style and expense, into the Greco Roman period, when portrait panels became a distinctive late addition to the wrapped body, before Christianity's spread through Egypt in late antiquity, with its different theology of bodily resurrection, brought the practice to an end. Egypt's mummification is the best known example worldwide, but it is not the oldest: the Chinchorro culture of the Atacama coast in what is now northern Chile and southern Peru practiced deliberate mummification of their dead, including notably of children, several thousand years before Egyptian practice began, a parallel and independent development that specialists in mummification studies treat as a distinct tradition rather than as an influence on or a copy of the Egyptian case.