The Twenty-First Dynasty was established by successors of Herihor and Smendes who continued to rule Upper and Lower Egypt separately from Thebes and Tanis. But by this period external threats from Libyan invaders and others were eroding Egypt's power to defend itself. Eventually both Upper and Lower Egypt succumbed to foreign invasions. Libyan warriors who established their own Twenty-Second Dynasty drove the Tanites from power.

Upper Egypt held out longer against Nubian invaders until being overrun by the armies of their ruler Piankhi all the way to Memphis. Piankhi's brother Shabaka marched north to conquer the Delta and reunite Upper and Lower Egypt under the Twenty-Fifth Dynasty of Nubian Kings (747-656BC). During this period there was an artistic and cultural revival. The Twenty-Fifth Dynasty ended when Assyrian armies captured Memphis and attacked Thebes, driving the Nubian pharaoh Tanutamun back to Nubia.

The Assyrians found a willing Egyptian collaborator in the form of a prince from the Delta. Psammetichus I governed on behalf of the Assyrians until they were forced to withdraw their forces to wage war against the Persian Empire. On the departure of the Assyrians, Psammetichus I declared himself pharaoh and established the Twenty-Sixth Dynasty, ruling over a re-united Egypt from his capital at Saïs in the Delta. This was to be the last great Pharaonic age which witnessed the revival of majestic art and architecture and the introduction of new technologies.

Gradually, though, the power of the kingdom eroded due to invasion, ending ignominiously when Amasis, "the Drunkard", was forced to depend on Greek forces to defend his Kingdom against the onslaught of Persian imperial armies.

The Persians first invaded Egypt in 525BC, initiating a period of foreign domination of the country which lasted until 1952, when an Egyptian republic replaced the monarchy of King Farouk. The conquering Persians established the Twenty-Seventh Dynasty (525-404BC) which ruled Egypt with an iron hand.

The Persians, under the emperors Cambyses and Darius, completed a canal connecting the Nile with the Red Sea which had been started by the Twenty-Sixth Dynasty king Necho II. They also constructed temples and a new city on the site of what is now called Old Cairo. This was called Babylon in Egypt.

The harshness of Persian rule resulted in revolts against the Persian satraps Xerxes and Artaxerxes which led to the Twenty-Eighth dynasty of the Egyptian ruler Amyrtaeus and his successors. The Egyptian kings of succeeding dynasties were under continual attack by Persians until the Thirtieth and final Pharaonic dynasty was overthrown by Artaxerxes III, remaining under Persian domination until the arrival of Alexander the Great in 332BC.