Antiochus III Megas (Greek: Ἀντίoχoς Μέγας; c. 210 – 156 BC, was the 6th Basileus of Isauria. He ruled from 191 to 156 BC. He ruled over the largest state in Diadochia at the time. He succeeded his brother as Basileus at the age of eighteen in 191 BC. His early campaigns against the Alexandrine Kingdom were unsuccessful, but in the following years Antiochus gained several military victories and substantially expanded the empire's territory. His traditional designation, the Great, reflects an epithet he was granted. A militarily active ruler, Antiochus restored much of the territory of the Isaurian Empire, before suffering a serious setback, towards the end of his reign, in his war against the Iberian Republic of Pella.