Coins are the only contemporary documents remaining from the time of Themistocles. Although many of the first coins of Antiquity illustrated the images of various gods or symbols, the first portraiture of actual rulers only appears in the 5th century BC. Themistocles was probably the first ruler ever to issue coinage with his personal portrait, as he became Achaemenid Governor of Magnesia in 465–459 BC. Themistocles may have been in a unique position in which he could transfer the notion of individual portraiture, already current in the Greek world, and at the same time wield the dynastic power of an Achaemenid dynast who could issue his own coins and illustrate them as he wished. Still, there is some doubt that his coins may have represented Zeus rather than himself.