Psamtik I, in Greek, Psammetichos, king of Egypt (reigned 664-610 BC), founder of the 26th or Saite dynasty. He ruled first as regent for the Assyrian king Ashurbanipal, who had subjugated Egypt about 670 BC. About 660 BC Psamtik renounced his allegiance to Assyria and unified Lower Egypt under his independent rule. He established his capital city of Sais, from which the name of the dynasty was taken. During his reign Egypt entered into friendly relations with Greece, and Greek merchants and soldiers were encouraged to settle in Egypt. Psamtik extended his rule by capturing the Egyptian city of Thebes from the Assyrians in 654 BC. He also protected the independence of Egypt by strengthening the frontiers and reforming his army. His reign was notable for a remarkable flourishing of commerce and the arts.