Historians have universally agreed that King Alara unified Upper Nubia around 780 BC, declaring Napata (near Jabal Barrkal, Karima, North Sudan) the capital. The job was completed by his successor King Kashata when Lower Nubia joined the crown. Nubia had been united and Kashata claimed for himself the title Pharaoh. But that was not the end of it; following suit was Pharaoh Piye, better known in history as Pharaoh Piankhy, conqueror of Thebes and founder of Egypt's 25th Dynasty, the dynasty of the Black Pharaohs.
Good long article.