With the Third Intermediate Period there was a shift of control to the Delta. The unstable political conditions of the times are reflected in a lack of much archaeological evidence there, but later rulers also appropriated monuments of this period for their own buildings, which has also limited the surviving evidence. Tanis became the capital of the 21st and 22nd dynasties, while the independence of a Theban polity centered on the estate of Amen of Karnak waxed and waned. In the later new Kingdom the delta had become home to increasing numbers of Libyans, and the kings of the 22nd, 23rd, and 24th dynasties were of Libyan descent (as were some of the kings of the 21st dynasty). With these dynasties, which overlapped in time, political fragmentation continued in Middle Egypt and the delta. Egypt was finally reunified in the 25th dynasty - by Kushite rulers from Upper Nubia.
The last pharaonic dynasties (26th-31st) are grouped together in what is called the Late Period (among which the 27th and 31st dynasties were times of Persian domination). The 26th dynasty, the origins of which were at Sais in the delta, was a period of indigenous rule, economic prosperity, and expanding trade and military activity abroad - which are also visible in the art and monuments of this period. But Egypt during much of the first millennium Bc faced successive invasions by foreign powers - Nubians, Assyrians, Persians, Macedonian Greeks, and finally Romans. Although pharaonic culture and ideology are evident well into the 4th-5th centuries AD, the rulers of Egypt were outsiders.
An Introduction to the Archaeology of Ancient Egypt, Second Edition. Kathryn A. Bard. © 2015 John Wiley & Sons, Inc. Published 2015 by John Wiley & Sons, Inc.