[this is one of *those* topics for the Catastrophism list, as well as being a GGG topic]The Assyrian Conquest: The Sequence of DynastiesThe transition of power from the Eighteenth to the Nineteenth Dynasty is regarded as an obscure period of Egyptian history. The circumstances under which the Nineteenth Dynasty was established are said to be unknown. This Dynasty is one of the most famous successions of pharaohs—Ramses I, Seti I, Ramses II, and Merneptah. Still another name is preserved, that of Haremhab. He belonged neither to the Eighteenth nor to the Nineteenth Dynasty; he was not a descendant of Akhnaton, nor was he an ancestor of the Ramessides. He is supposed to have ruled Egypt during an interregnum. It is not apparent why he was “chosen to be king” and to administer Egypt. Nothing is known of his end. The idea so often expressed that Haremhab was a successor of Ay is baseless. We shall encounter Haremhab later in this volume—but he lived one hundred and fifty years after Ay... the Libyan and Ethiopian dyansties followed closely the Eighteenth Dynasty and preceded the Nineteenth and the Twentieth. This result of the present reconstruction is probably the most unexpected of all. Yet in Peoples of the Sea (1977) the time of Ramses III and with him the entire Twentieth Dynasty have already been shown to belong into the fourth century; and the volume Ramses II and His Time (1978) has carried the task of identifying the Nineteenth Dynasty as synonymous with the Twenty-sixth, that of Necho I, Psammetichus, Necho II, and Apries. The so-called Nineteenth Dynasty will be found to have been displaced not only by the five hundred and forty years of error in the dating of the Eighteenth Dynasty, but also by an additional one hundred and seventy years—the duration of the Libyan and Ethiopian dominations over Egypt: and the total error will be found reaching the huge figure of seven hundred years
Immanuel Velikovsky
A lot of scholars consider Immanuel Velikovsky a crackpot. I don’t know of anyone who accepts his radical redating of dynasties. The fourth century is pretty well-documented by ancient standards.