The asphalt from the Dead Sea was an important item of trade in antiquity. Among its many uses, the most widespread was its export to Egypt for use in the mummification process, albeit at a relatively late date; that is, post 1000 bc. Its use became particularly important in the Ptolemaic–Roman period, as demonstrated by a war in the fourth century bc specifically to gain commercial control of this product. Although the reasons why the Egyptians wanted Dead Sea asphalt at this specific time are nowhere specified, the answer may lie in its increasing availability as a (partial) replacement for the plant resins used previously. A review of the historical literature shows that Dead Sea asphalt was used for at least two millennia as a biocidal agent in agricultural practices. It is proposed that the reasons for using Dead Sea asphalt in the mummification process are due to its dual role; first, as an external mechanical shield, when smeared on the exterior of mummy wrapping, to prevent ingress by insects, fungi, bacteria and moisture; and, second, as a biocidal agent (perhaps due to its high sulphur content), which prevented the flesh from decaying, the prime concern for the ancient Egyptians.