The dating of the Prima Porta piece is widely contested because there is a representation on the breast plate signifying the Roman eagles' return by the Parthians in 20 B.C. It is thought to be a copy of a bronze original. The sculptor may have been Greek. This original, along with other high honors, was vowed to Augustus by the Senate in 20 BC and set up in a public place. The marble statue, however, was found in the villa of his wife, Livia.
It is also contested that this particular sculpture is a reworking of a bronze original, possibly a gift from Tiberius Caesar to his mother Livia (since it was found in her villa Ad Gallinas Albas in the vicinity of the ninth mile-marker of the via Flaminia, and close to a late Imperial gate called Prima Porta) after Augustus' death and in honor of the woman who had campaigned so long for him to become the next Caesar. This would explain the divine references to Augustus in the piece, notably his being barefoot, the standard representation of gods or heroes in classical iconography. Also, the reliefs in the heroic cuirass depict the retrieval of Crassus' standards captured by the Parthians, an event in which the young Tiberius himself took a part, serving as an intermediary with the Parthian king, in the act that is shown in the central scene of the armor, possibly his grandest service to his adoptive father Augustus. With the introduction of Tiberius as the figure responsible for the retrieval of the standards, he associates himself with Augustus, the emperor and the new god, as Augustus himself had done previously with Julius Caesar.
Under this hypothesis, the dating of the statue can be placed during the first years of Tiberius' reign as emperor (AD 14 — AD 37).