Gyges was the founder of the Mermnad dynasty of Lydian kings. The dates of his reign are uncertain but have been tentatively estimated as c. 687 – c. 652 BC. According to Herodotus, he reigned for 38 years. He was a bodyguard of his predecessor Candaules whom he assassinated in order to seize the throne. His action was approved by the Delphic Oracle and that decision prevented civil war in Lydia. Once established on the throne, Gyges devoted himself to consolidating his kingdom and making it a military power.
He captured Colophon, Magnesia on the Maeander, and probably also Sipylus, whose successor was to become the city also named Magnesia in later records. Smyrna was besieged, and to the north, the Troad was brought under Lydian control. Gyges pushed back the Cimmerians, who had ravaged Asia Minor and caused the fall of Phrygia. During his campaigns against the Cimmerians, he failed to engage the help of the Assyrians and turned instead to Ancient Egypt, sending his Carian troops to assist Psammetichus. Gyges later fell in a battle against the Cimmerii under Dugdamme, and was succeeded by his son Ardys of Lydia.