“the first instance of Egypt being ruled by individuals of a foreign origin”
Even this is a dubious conjecture, since it ignores all the evidence that the Mesopotamians came in and did a little “regime change” around the 1st Dynasty.
There is no compelling evidence of that, although that is one of David Rohl's claims. Sargon the Great, founder of the Akkadian Empire, records that Musri (Egypt) paid tribute to him. Egyptian disunity was probably more the rule than the exception, with the various city-states coming into and going out of dominance, a pattern also seen in Mesopotamia, until Sargon.
Egyptian unity during the Old Kingdom appears to have been fragile. At its peak, the 4th dynasty was in charge, but there was a dynastic struggle (internal to the ruling family, Khufu's eldest son succeeded him, he died early, his young son succeeded him, then uncle Khafre took over). The 5th dynasty was apparently descended from the 4th, but lost control of the north (lower Egypt) or at least of Giza, evident from the burials of the pharaohs in the older southern areas and in mastabas instead of pyramids.
There is no evidence of that, although that was one of David Rohl's claims. Sargon the Great, founder of the Akkadian Empire, records that Musri (Egypt) paid tribute. Egyptian disunity was probably more the rule than the exception, with the various city-states coming into and going out of dominance, a pattern also seen in Mesopotamia, until Sargon conquered all Sumerian city-states.