the time when these traders were able to supply the nations of Europe with abundance of bronze in exchange for their products, at, say 1000 to 1200 B.C., as the earliest probable period; and possibly from one to two centuries would be a sufficient allowance for the complete penetration of the trade throughout Europe. But of course wars or migrations might retard or accelerate the process; and there may have been isolated spots in which a partial stone period extended up to those comparatively recent times in which first the Greek trade, and afterward the entire overthrow of the Carthaginian power by the Romans, terminated forever the age of bronze and substituted the age of iron. This would leave, according to our ordinary chronologies, at least ten or fifteen centuries for the postdiluvian stone period in Europe and Western Asia, a time quite sufficient in our view for all that part of it represented by such monuments as the Danish shell-heaps or the platform habitations of the Swiss lakes; leaving the remains of the prehistoric caverns and river gravels for the antediluvian period. A few facts in illustration of these points, and also of the Biblical history, may be mentioned here. We know perfectly that the early Chaldeans of the Euphratean valley were acquainted with the use of metals--bronze certainly, and at a very early date iron; yet flint knives and other implements of stone are found under circumstances which show that they were used in the palmy days of the Assyrian empire. The inhabitants of Egypt were acquainted with bronze and iron long before the date of the Exodus, yet the Egyptians used stone knives for some purposes up to a comparatively modern time. Joshua used stone knives for the purpose of circumcision; and according to Herodotus there were Ethiopians in the army of Xerxes who used stone-tipped arrows. If any antiquarian were to stumble on the "hill of the foreskins"--a mound under which were buried in all probability the multitudinous flint flakes used in the circumcision of the thousands of Israel--or the grave in which some of the Ethiopian auxiliaries of Xerxes were buried with their flint arrow-heads and javelins of antelopes' horn, how absurd would be the inference that these repositories were of the palaeolithic age. Nay, so late as 1870 a traveller was informed that the Bagos, a people of Abyssinia, still made and used stone hatchets and flint knives.[121]