The trend with current field work in lower Egypt (Nile Delta) supports Romer's view, but there can be no doubt the expansion of Naqada culture also included military power, in fact Naqada IIc expansion went beyond lower Egypt into the Levant. In my opinion you should read "Before The Pyramids - Origins of Egyptian Civilization" (Oriental Institute Museum Publication 33 - The Oriental Institute of the University of Chicago, ed. Emily Teeter, 2011).

In OIMP33 you will find the foundations of Romer's reasoning, basically the Maadi-Buto culture was comprised of neolithic style Chiefdoms at the time Naqada IIc culture was already a well functioning state in its own right, but the archaeologic strata in the Delta reveals the Maadi-Buto culture wained slowly over centuries until disappearing altogether by the arrival of Naqada III period... Lower Egypt appears to have been absorbed by long term acculturation of Naqada, this is not to say along the way conflicts didn't occur in certain districts or cities resisting, the Narmer Palette could represent one of many Lower Egyptian cities who would not comply and just as easily represent a battle from the expansion into the Levant. Unification was a long political, cultural and military process, not a conquering war. There's also a case made by Wilkinson that the Red Crown of Lower Egypt had it's origin from Upper Egypt, the point being that the Red Crown was already existing in Lower Egypt long before Dynasty 0.

B.A.Hokom