Explaining the Timeline
This timeline explains one of the possibilities for what might have happened if Neo-Babylonia, hence referred to as Babylon, had not lost the Battle of Opis. This eventually leads to a complete and utter change in history, with more barbaric times throughout history. Enjoy.
Point of Divergence, September-October 27, 539 B.C.E
The PoD here is is at the Battle of Opis, where in the OTL, Babylon is defeated by the armies of Cyrus II, king of Persia. In this timeline, Babylon sends two armies, one to engage the Persians in a frontal attack, and the other to flank them. While crossing behind, the second army encountered a small force sent by the Persians to do the same. The force was small, but was skilled in fighting while outnumbered. The flanking forces met, and eventually, the Babylonians win, although not without a price. More than half of the flanking force is lost, and the remainder are left without a leader. Eventually, a soldier, whose name is not recorded, leads the force into the fray against the Persians, and helps to turn the tide against them. The Persians, defeated, retreat back across the Tigris.
539 B.C.E - 419 B.C.E
After the victory at the Battle of Opis, the Babylonians gathered their armies in a push to keep Persia away. By 500 B.C.E., the Babylonians have attacked and gained ground back along their borders. They also annex places farther south, and sent an army to Cyprus. Cyprus, however, repulsed the attack, and was left alone for a few centuries. Meanwhile, the Persians suffer from a famine and are attacked by a newer Middle Asian empire, the Əlaqə Dünya, (literally meaning "known world" in Azerbaijani.) The Dunyans amass an army and move in on Persian territory, especially the city of of Trapezus. By the mid-to-late 400s, the Persian Empire was near collapse from the twin assaults from the north and south. The war on Persia came to a climax when the Babylonians and the Dunyans amassed two armies and sent them to Susa. The Persians also sent an army to the Dunyan capital, Dünya şəhər (which means world town.) The Babylonian army continued on at full force, but part of the Dunyan army peeled off from the rest and was sent to stop the Persians. The first battle to take place was the battle of Susa, the last Persian stronghold.
The Battle of Susa
As preparation for the battle, the city is set on fire. To escape and prepare for battle, the Persians open the east and west gates. They exit out of the west gate, and allow citizens who did not flee earlier to get away through both. As the Babylonians set up camp, the Dunyans arrived on the other side of the city. All of the armies settle in for the night. Late into the night, the Persians have archers fire flaming arrows down into both camps. In response, the Dunyans and Babylonians mount their forces, including chariots, (which the Babylonians had given to the Dunyans as part of a trade,) and attack. The Persians, surrounded, are routed and slaughtered. The Dunyans, who were particularly vicious victors, ride around the farms and salt them. Persian backup arrives too late, and is slaughtered as well. The Babylonians and Dunyans celebrate by raiding the city's food stores, which miraculously survived the fire, and feasting. A few weeks later, they receive a messenger from Dünya şəhər, telling the results of the battle.
Destruction of Dünya şəhər
The Persian army met up with the Dunyan army halfway between Dünya şəhər and Susa. The Persian force, before it had been seen, was reported by spies to be twice as big as it appeared to be now. The Persians, as soon as they came into range, sent archers ahead and fired. The Dunyan army survived, but with their forces cut in half. They mounted the chariots, but the other half of the Persian force had been sent around, as a flank, and utterly destroyed the chariot teams and infantry. The Persians, almost unchallenged, marched the rest of the way to Dünya şəhər and razed it to the ground. The Persians then attempted to retreat back to Susa, but encounter the twin armies and are destroyed.
Rise of the Egyptians
The Persians, being cut off from Egypt by Babylonia, were never able to reach Egypt, and so the Saite Dynasty flourished. In the wake of the Persians' destruction, they rose to be the prominent power in Northeastern Africa,
spreading all the way to modern-day Sudan and Libya. The Babylonians were their next target, and so in 394 B.C.E. they invaded Babylonia and destroyed Babylon, the capital. The Egyptians continued their surprise attack unhindered and went on to conquer the former Persian empire's territory and the rebuilt Dünya şəhər. By 350 B.C.E., almost a quarter of Africa and all of the Middle East was under Egyptian control.