Manetho of Sebennytos in the Nile Delta was an Egyptian priest and historian who flourished in the 3rd century BC. He produced a significant history of Egypt in three volumes, Aegyptiaca[1373.40], but unfortunately only fragments have survived(b).
His lists of Egyptian kings continue to be used as one of the pillars of Egyptian chronology. Interestingly, he would seem to claim that the earliest of the kings ruled in a foreign land. This has been taken by some, such as R. Cedric Leonard, to mean Atlantis(a).
Also relevant is that Manetho wrote of the ancient Egyptians counting time in months rather than years – “The year I take, however, to be a lunar one, consisting, that is, of 30 days: what we now call a month the Egyptians used formerly to style a year.”