The article is a historical analysis of a Greek inscription discovered in Zela, one of the cities in the Kingdom of Pontus. This epigraphical document was left by Polemo (king of Pontus, named in this inscription without the royal title) and dedicated to Caesar Augustus, called as his benefactor. The author supposes that the inscription appeared about 26 BC, when Polemo I, made king of Pontus in 37 BC by Marcus Antonius, was included into the list of Roman allies by Caesar Augustus, and once again, after Marcus Antonius, his first Roman patron, had to be declared king by the Roman emperor. This document is important from the point of view of Roman eastern policy and the attitude towards the client Greek states, their kings and dynasts. It also proves that the city of Zela was initially included into the Pontic state of the Polemonids, and Polemo I, who before the battle of Actium had lost his royal title as Marcus Antonius’ friend, was trying to get it again and keep his throne with Augustus’ help.