After his deposition in 491 BC Demaratus had fled to Persia, where king Darius I made him ruler of the cities of Pergamon, Teuthrania and Halisarna. About a hundred years later Eurysthenes and his brother Prokles reigned over the same cities; their joint rule is at least attested for the year 399 BC.[1]
Xenophon and the Ten Thousand received some support from Prokles in facing Achaemenid troops, at the beginning of their campaign into Asia Minor.[2] According to Xenophon (Anabasis, 7.8.8-17), when he arrived in Mysia in 399, he met Hellas, the widow of Gongylos and probably daughter of Themistocles,[3] who was living at Pergamon. His two sons, Gorgion and Gongylos the younger, ruled respectively over the cities of Gambrium, Palaegambrium for Gorgion, and Myrina and Grynium for Gongylos. Xenophon received some support from the descendants of Gongylos for his campaign into Asia Minor, as well as from the descendants of Demaratos, a Spartan exile who also had become a satrap for the Achaemenids, in the person of his descendant Prokles.[4][5]
The coinage of Prokles displays one of the earliest portraits of a Greek ruler on a coin.[6]
The city of Pergamon was later taken over by the Spartan general Thibron, who was fighting against the Achaemenid Satrap of Lydia and Ionia Tissaphernes.[7]