Egypt vs. the World
Turns 451-550
The assault upon the Egyptians was seen as the greatest mistake of the Romans. While the Persians would fall under their reign as a result of a parallel invasion, the Egyptians repulsing the Romans fractured the mindset that the armies of Rome were unbeatable. More invasions would come, but all would be repulsed by the Egyptians. Eventually, the continued defiance of the Egyptians led to massive revolts to spring up across the entirety of the empire, leaving the Romans with only the Italian Peninsula remaining. Soon that would fall to infighting, and the Roman civilization would be no more.
Egypt would be unable to take advantage of this weakness, however. With the conquering of Persia, the nation was obligated to join the Roman war upon the Egyptians. Furthermore, due to bribes of Kedu to Nubian forces being discovered, the Ethiopians also declared war upon the Egyptians. Egypt was at war with every single neighbor it had. If Rome had not collapsed, then it is likely that the Egyptians would not have held. However, the collapse of Rome allowed them to survive. The Greeks, having broken away from Roman authority before Persia had been fully conquered, agreed to a cessation of hostilities between their two nations. After the Romans fell, so did the Persians. As for Ethiopia? Egypt sacked their capital and quickly took over the rest of their cities.
This move, while glorious, proved disastrous over the long term. Many centers of learning funded by the Pharaohs had to be shut down due to the sheer cost required in order to maintain the lands they conquered. Furthermore, the former Roman invaders of Kebu, who had marched west into Nubian lands and would eventually interbred with the natives to create the Mali civilization, had taught the Nubians their strategies. This resulted in many massive raids into Egypt that destroyed all the ancient improvements that had been constructed in the Nile river valley, as well as those made to replace them. As well, massive plagues struck that destroyed large portions of the Egyptian population. Within the new holdings, all but one of the captured Ethiopian cities were either razed or captured by Impi tribesmen.
Egypt had not fallen from this, however. The Pharaohs still held dominion, in large part thanks to the continual destruction of their enemies by the elite former expeditionary force, and trade was beginning to start up once more. Furthermore, with the destruction of most of the Ethiopian holdings, they could more effectively administer what remained. Progress once more began and the Egyptians moved on into the future.
To give a rough idea of just how behind I am, Metal casting and Writing are the furthest along in the tech tree I am at. It's late 500 AD.
Oh, and to give you an idea of how large the barbarian invasion was, 2 stacks of 7 strength 4 Nubian Medjays (which have +50% vs Melee and 2 first strikes) as well as 4 strength 6 Nubian Berber cavalry that have +50% against melee, a strength 8 cavalry unit, and 3 or 4 strength 5 Impi Warrior units that have +100% against Cavalry. The twin stacks of 7 spawned in the middle of my territory. Mod does not fuck around when it wants you to die a 'historic' death. If you want to live, you must earn it.