What held the Egyptians back?
Probably the bronze age collapse, quite a scary event that extinguished trade routes and literacy.
The Late Bronze Age collapse was a time of widespread societal collapse during the 12th century BC, between c. 1200 and 1150, and was associated with environmental change, mass migration and destruction of cities. The collapse affected a large area of the Eastern Mediterranean and the Near East, in particular Egypt, eastern Libya, the Balkans, the Aegean, Anatolia, and the Caucasus. It was sudden, violent, and culturally disruptive for many Bronze Age civilizations, and it brought a sharp economic decline to regional powers, notably ushering in the Greek Dark Ages.