Cerethrius was a GallicThe Oxford Illustrated History of Prehistoric Europe (Oxford Illustrated Histories) by Barry Cunliffe,2001,page 380 king in

Thrace Thrace (; el, Θράκη, Thráki; bg, Тракия, Trakiya; tr, Trakya) or Thrake is a geographical and historical region in Southeast Europe, now split among Bulgaria, Greece, and Turkey, which is bounded by the Balkan Mountains to t ...

. He was defeated in 277 BC, by

Antigonus II Gonatas Antigonus II Gonatas ( grc-gre, Ἀντίγονος Γονατᾶς, ; – 239 BC) was a Macedonian ruler who solidified the position of the Antigonid dynasty in Macedon after a long period defined by anarchy and chaos and acquired fame for ...

at the Battle of Lysimachia.

References

Celtic warriors Gaulish rulers Ancient Thrace 3rd-century BC rulers {{Ancient-Thrace-stub