Sadyattes (; ; reigned 630–) was the third king of the Mermnad dynasty in Lydia, the son of Ardys and the grandson of Gyges of Lydia. Sadyattes reigned 12 years according to Herodotus.
Reign
Background
Sadyattes came to power during a period of severe crisis that Lydia was facing because of several waves of invasions by the Cimmerians,
In 630 BC, that is, in Ardys's 49th regnal year, the Thracian Treres tribe, who had migrated across the Thracian Bosporus and invaded Anatolia, under their king Kobos and in alliance with the Cimmerians and the Lycians, attacked Lydia.
Reign
Sadyattes's reign was even more short-lived than that of his father Ardys: Little is known about the reign of Sadyattes except that he began a war with the Ionian Greek maritime city of Miletus.
End of reign
Sadyattes's reign ended in 618 BC. It is possible that, like his grandfather Gyges, he died fighting the Cimmerians. Alternatively, Sadyattes might have been deposed for failing to protect Lydia from the Cimmerian attacks. and in alliance with the Lydians, the Scythians under their king Madyes entered Anatolia, expelled the Treres from Asia Minor, and defeated the Cimmerians so that they no longer constituted a threat again, following which the Scythians extended their domination to Central Anatolia until they were themselves expelled by the Medes from Western Asia in the 600s BC.