Who dated Antigonus II Gonatas?

Antigonus II Gonatas (Ancient Greek: Ἀντίγονος Γονατᾶς, Antígonos; c. 320 – 239 BC) was a Macedonian Greek ruler who solidified the position of the Antigonid dynasty in Macedon after a long period defined by anarchy and chaos and acquired fame for his victory over the Gauls who had invaded the Balkans.