Egypt, with the Nile, was hands down one of the richest areas in the world until recent history, due to the massively advantageous agricultural output potential thanks to the predictable nature of the great river. For many empires across history it was also a "key" province, most notably for the Romans, where the Nile provided crucial food supplies, tax revenue, and access to Indian trade routes which kept the empire afloat. It was so important that no senator could enter the province without the Princep's direct approval, there was even a huge scandal when the heir apparent Germanicus made a trip into Egypt when Tiberius was still emperor. Besides that, ancient Egypt was almost on China's level as a great cultural force, even assimilating conquerors due to the strength and inertia of their religious beliefs and customs. The Ptolemy's had a notoriously hard time in Hellenizing the Coptic peoples and Cleopatra was the first Greek monarch to learn the native language.


My question is, why did a region that was so strong agriculturally, economically, and culturally never make a great world empire of its own? Egypt and Assyria were the two major states to survive the Bronze Age collapse, but only Assyria capitalized on the massive power vacuums created by the collapse of most of the civilized world and would eventually conquer Egypt as well. When the Assyrians fell, another power vacuum opened up, but once again Egypt failed to capitalized and was eventually conquered by the Achaemenids. Egypt then had another chance under the Ptolemaic dynasty, but the nature of the wars of the Diadochi was that any two powers never let the third become too powerful, so the Ptolemies never expanded far out of the Levant with spheres of influence in southern Greece.


By the time Rome gobbled up Ptolemaic Egypt during the civil wars, Egypt had lost its shot at a large independent empire until the medi period under the Mamluks. What held Egypt back from leveraging its massive advantages into creating an empire to rival the Persians, Romans, and Assyrians?