| This Year In|
- 253-260: Reign of Valerian with his son Gallienus.
- 257-260: Valerian orders the extermination or forced conversion of any Christians within the Empire, as well as the destruction or confiscation of their property.
- 260-268: Reign of Gallienus.
- 260-268: Reign of Gallic Emperor Postumus.
- 260-273: Gaul and Britain secede from the Roman Empire under a series of Gallic Emperors, but later rejoin with Rome. Eastern provinces Syria, Palestine, Egypt and Asia Minor likewise break away as the Palmyrene Empire.
- 260-273: Gallic Empire. Gaul and Britain secede from the Roman Empire under a series of Gallic Emperors, but later rejoin with Rome.
- Valerian is captured by Persians. Generals Quietus and Macrianus are elected by their troops as Emperors, and successfully lead the troops out of Persia, only to face Emperor Gallienus and lose.
- Ignenuus takes advantage of the unstable situation to have himself declared Emperor, but dies facing legitimate Romean forces. Regalianus gets elected Emperor by eastern provinces almost by accident. He saves his people from the Sarmatians, but gets assassinated by his own people.
- Around this time, Plotinus and Porphyry write about Neoplatonism, also known as Theurgy, a pagan philosophy based on the works of Plato.