Idk, maybe some roman style scenario, decadence https://www.quora.com/How-did-the-ancient-Egyptians-disappear >>But if you mean how did the ANCIENT Egyptians disappear, well, they were invaded by the Persians in the 6th century BC, when the last Pharaoh Psamatik III was killed in the battle of Pelusium. All kind of foreigners came to settle in Egypt;Greeks, Jews, Syrians. Two centuries later, Egypt fell to Alexander the great, then the Ptolemaic dynasty, until the first century BC, when Egypt became a province of Rome under Julius Caesar 30 BC. ... >>Following internal dissension and weakness, Egypt was conquered in succession by Assyrians, then Persians, and finally by Alexander the Great. The Greeks had the greatest impact. They adopted some of the Egyptian customs, including mummification, and the worship of the Egyptian goddess Isis spread throughout the eastern Mediterranean, while at the same time, Egyptians adopted Greek ways. Over time all sorts of religions cropped up in Egypt, including Jews and the Roman one and many others. The ability to read the hieroglyphs was lost, and the earlier temples abandoned. Essentially, the ancient culture simply was dissolved into the new cultures that came in through invasion and trade. ... >>Egypt was conquered by Persia in 525 BC, the Alexander the Greek in 330 BC, the Romans in 50 BC and the Arabs in 450 AD and the Muslims in 690 AD. Then eastern European Mameluks in 1250 AD, Then the Ottomans in 1517 AD and Napolean in 1698. That is 2200 + years of foreign domination. THE ANCIENT EGYPTIANS WERE FINISHED AT THE END OF THE 5TH DYNASTY OR OLD KINGDOM. Sounds like it