The resins, in particular, are based upon aromatic trees grown in the furthest reaches of the west, and thus unobtainable of late.
Modern Xorinthian embalming grew from early Prandoran attempts to preserve rulers and great wizards. Formalin Mustard, as a fluid, is infused to replace the blood causing thorough and complete preservation of the body.  This total preservation of the body is far beyond the crude early attempts of many civilisations.