Galatia was a region of Central Anatolia settled by the Gauls after their invasions in the mid-3rd century BC. From then until 62 BC, the Galatians ruled themselves by means of decentralized Tetrarchies, but in 62, the Romans established a Kingdom of Galatia, which lasted around 35 years.
References
List of kings of Galatia Wikipedia(Text) CC BY-SA