PugJesusEuropean archeological academia was in a... primitive state at the time.
Explanation: In the 19th century, Egyptian mummies that were found in the course of European archeological expeditions were sometimes sold off. Some would be acquired by collectors, others… ground up for use as paint or quack ‘medicine’.
… it was not the best of times for European archeology, a then-new discipline.
fakeman_pretendnamePotentially making things worse, “mummy brown” paint was very popular for a time, and more in demand than the supply of “freshly-ground mummy dust” available, so (allegedly) manufacturers started cutting/replacing it with the freshly burnt corpses of criminals and slaves.