During the early centuries AD, Palmyra was a city subordinate to Rome and part of the province of Syria Phoenice. In 260 the Roman emperor Valerian marched against the Sassanid Persian monarch Shapur I, who had invaded the empire's eastern regions; Valerian was defeated and captured near Edessa. Odaenathus, formally loyal to Rome and its emperor Gallienus (Valerian's son), was declared king of Palmyra. Launching successful campaigns against Persia, he was crowned King of Kings of the East in 263. Odaenathus crowned his eldest son, Herodianus, as co-ruler. In addition to the royal titles, Odaenathus received many Roman titles, most importantly "corrector totius orientis" (governor of the entire East), and ruled the Roman territories from the Black Sea to Palestine. In 267, when Zenobia was in her late twenties or early thirties, Odaenathus and his eldest son were assassinated while returning from a campaign.