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The first problem with Manetho's dynasties was that the Egyptians left few clues as to which dynasty followed which; they weren't interested in recording which dynasties ended in a revolution and which simply died out.
More serious is that the original text of Manetho is no longer available; what we have are garbled editions quoted by two late Roman writers (Eusebius and Africanus), plus an excerpt from Josephus.
While most sites are adorned with inundations of praise to the builder of the structures, unfortunately, the Giza complex is devoid of such engravings or inscriptions (exceptions discussed earlier).
In itself, the absence of information is significant.
"Furthermore, it looks like Manetho "cooked the books," stretching out the history of Egypt as long as he could get away with, by adding years which did not exist, listing kings who shared the throne (co-regencies) as ruling alone, and dynasties as proceeding one after another, when many may have overlapped, especially during the intermediate periods.
It is clear that any results from that line of research are in themselves complicated by the interpretation of the cartouches exact meaning. We know that the use of Giza was not restricted to the 4th dynasty pharaohs because of earlier finds in the area.
The Royal list of Abydoss (Right) - In the hall of records at the temple of Abydos, Seti I and his young son, the future Ramasese II are shown worshipping the cartouched names of 76 of their ancestors.
Unacceptable predecessors such as Hatshwpsut and Akhenaten and the Pharaohs from the Amarna period are omitted from the list.
The debate over when the Giza complex was constructed is still ongoing.
Erosion patterns from the Sphinx enclosure suggest a far older date than subscribed by Egyptologists and there are several at Giza discoveries from before the 4th dynasty that clearly suggest the complex was in use before the pyramids are said to have built.