Source: A History of Ancient Egypt by Nicolas Grimal, Blackwell Publishers 1999, pgs 334-353
Nubia was heavily Egyptianized by the 18th Dynasty it was also known as Kush. It split away from Egypt after the disintergation of the empire established by Ramesses II. During these years Nubia maintain much of it's 18th Dynasty Egyptianization, in particularly in it's religion and worship of Amun. Kashta c. 760 BCE, was the first Nubian King to actually cast an eye at ruling Egypt. His capital was Napata, originialy founded by Thutmosis III of the 18th Dynasty. Egypt by the time of Kashta had been ruled by the Libyan Pharaohs, and was acutally breaking up into it's ancient historical divisions of Lower Egypt and Upper Egypt once again. Kashta, consolidated his father's gains in Lower Nubia, and pushed on to as far was Aswan, giving himself a pharonic titulature with Maatre as his coronation name. He may even have pushed as far north as the Theban region.
However it was his son Piankhy who accended to the Kushite throne in 747 BCE continued his father's ambition into Egypt. He took Thebes under his protection and ensured that his siter Amenirdis I was adopted by the Libyian Divine Adoratrice Shepenwepet I, as her daughter and heir. By 736 BCE when she became the new Divine Adoratrice it appears that her brother was in control of the whole of Upper Egypt. The King of Sais, Tefnakht another of the Pharonic pretenders of the age united the kings of Hermopolis and Herakleopolis and declared war against the Kushites of Upper Egypt.
Piankhy defeated the Northern/Lower Egyptian coalition and became the new "unifier" of Egypt's Two Lands. He besieged Hermopolis, and they opened their gates to him. His troops pillaged Middle Egypt. Herakleopolis surrendered without waiting to be captured as the other cities were. He also recieved the surrender of Maidum and el-Lisht. By this time the Egyptian coalition had reassembled at Memphis, Piankhy besieged it and it also fell to him. He went on to Heliopolis and celebrated the cult of Ra and re-enacted the rites of his own coronation.
Of the kings that surrendered to Piankhy, only Tefnakht escaped he fled north into the Western Delta and as far south as Memphis, he declared himself to be King of Egypt about 720 BCE and is considered the founder of the short lived 24th Dynasty.
Piankhy after his coronation in Heliopolis headed back south to his capital Napata. Embarked on a great building program heavily dependent upon Egyptian traditions. He died in the 31st year of his Kushite rule in Napata. His younger brother Shabaka became the actual first Kushite Pharaoh of the 25th Dynasty. Piankhy is often just a seperate name between the dynasties of the 23rd (Libyans), 24th (the Sais) and the 25th Kushite Dynasty of his own family.
Shabaka, in his 2nd year as Pharaoh ended the 24th Dynasty and took complete control of Lower Egypt. During Shabaks' reign Assyria seriously began it's assult on traditional Egyptian Syrian/Palestine terroritory. It is believed that he even tried to get some kind of peace or at least a diplomatic agreement with Assyria.
Like his brother, Shabaka continued the policy of a return to traditional Egyptian values. He was succeeded by the sons of Piankhy, first by Shebitku and then Taharqa. Taharqa, ruled for 26 years. He would lose the throne to Assyria, and their puppet kings. He rebuilt many of Egypt's great temples from the Old Kingdom. In 671 BCE, the Assyrian King Esarhaddon, defeated Taharqa and seized Memphis, capturing the crown prince and various members of the royal family. Taharqa retreated to the south where he maintained control. The Assyrians followed south as Taharqa withdrew further into Kush proper. Of the Assyrian puppets only Necho remain loyal when the Assyrains returned to their own land. The Assyrians returned put Necho's son Psammetichus I, in control of all of Egypt.
Meanwhile, Taharga in the same year 665 BCE named his cousin Tantamani as heir, then died the following year in Napata. Tantamani embarked on a crusade to retake Egypt. He did retake Memphis but this was a short lived victory. The Assyrians returned in 664/663 BCE. King Ashurbanipal unleashed his armies, Memphis was retaken. Tantamani withdrew to Thebes, the Assyrians followed and as they were invading Thebes Tantamani fled to Napata. Thebes was sacked by the Assyrians, burnt, ravaged and all its temples treasures were pillaged.