The Third Intermediate Period was, on the whole, a period of decentralization and weakness. By the end of his reign, Ramesses XI (c.1099–1069 BC), the last king of the New Kingdom, was no longer in effective rule of the whole of Egypt. After his death, a branch of the Ramesside family ruled from Tanis (modern San al-Hagar) in the north-eastern Delta. Although the reign of this line of kings, the Twenty-First (c.1069–945 BC), was acknowledged throughout the country, Upper Egypt was in reality governing itself, headed by the powerful high-priest of the god Amun in Luxor, who simultaneously held the highest military office as well. Historians describe this period as a theocracy, since it was the god Amun who held the highest authority.
Sheshonq I, the founder of the Twenty-Second Dynasty (c.945–715 BC), came from a powerful Libyan family from Bubastis (modern Tell Basta) in the eastern Delta, which he made his capital. He managed to bring the country under his control, successfully campaigned in the Levant (the area of Palestine, Lebanon, and Syria), and undertook monumental construction projects. This short-term success could not reverse the overall trend of decentralization in Egypt and, after his death, the central government’s control over the country continued to slip.
By the time of the Twenty-third Dynasty, many areas were not only completely independent, but their respective rulers actually considered themselves kings, wearing royal regalia and bearing royal titles. During this time, the Nubian Kushite Kingdom, centered around Napata near the fourth cataract, was on the rise, until they began to invade Egypt. The Nubian, Twenty-fifth, Dynasty eventually conquered even Memphis under King Piye (c.747–716 BC), to whom all other contemporary Egyptians kings submitted themselves. This ushered into an era of great prosperity, art flourished, and many great monuments were built.
Simultaneously in the Near East, the Neo-Assyrian Empire had become a world power. It had expanded as far as Palestine, and a clash with Egypt became inevitable. Although he Kushite kings successfully defended Egypt, the Assyrians were ultimately victorious. The Kushites managed to reconquer Egypt as far as the Delta, but the Assyrians, headed by the great king Assurbanipal, retaliated, and sacked Thebes.