Manetho's lists, as they have come down to us, show a date of 5867 years B.C. for the accession of Menes. Of this period, we may say that we know 1750 years for the New Empire and the period of the Persians and the Ptolemies, from contemporary monuments and records, with such certainty that any possible error cannot exceed fifty or one hundred years. The Hyksos period is less certain, but there is no sufficient reason for doubting that it may have lasted for about 511 years. Manetho could have had no object in overstating the duration of the rule of hated foreigners, and a long time must have elapsed before the rude invaders could have so completely adopted the civilization of the subject race. The dates of the Middle Empire, to which Manetho assigns 1241 years, are more uncertain, and we can only check them by monuments for the eleventh, twelfth, and thirteenth dynasties. The length of the fourteenth Xoite dynasty seems to be exaggerated, and the later obscure Theban dynasties may have been contemporary with the rule of the Hyksos in Lower Egypt. Of the 2105 years assigned to the Ancient Empire, the first 1645 from Menes to the end of the sixth dynasty are well authenticated by monuments and inscriptions, and the 460 for the seventh, eighth, ninth, and tenth are obscure, though a considerable time must have elapsed for such a complete eclipse of the monuments and arts as appears to have occurred between the nourishing period of the sixth dynasty and the revival of the Middle Empire under the eleventh. We may say, therefore, that we have about 4000 years of undoubted history between the accession of Menes and the Christian era, and 1600 more years for which we have only the authority of Manetho's lists, and the names of unknown kings in genealogical records, with a few scattered monuments, and to which it is difficult to assign specific dates. This may enable us to appreciate the nature of the evidence upon which Mariette and so many of the best and oldest authorities base their estimates in assigning a date of about 5000 B.C. for the accession of Menes.