AD 244: Plotinus, Greek philosopher, escapes the bloodshed that accompanies the murder of Gordianus III and makes his way to Antioch. Back in Rome he founds his Neoplatonist school and attracts disciples like Porphyry, Castricius Firmus and Eustochius of Alexandria.
AD 247: Rome becomes 1,000 years old. The 1,000th anniversary is commemorated with the Ludi Saeculares festivals, celebrated throughout the Roman Empire.
AD 254: The Roman Empire is threatened by several peoples on their borders: the Germanic confederations, such as the Franks on the Middle Rhine, the Alemanni on the upper Rhine and Danube, and the Marcomanni facing the provinces at Noricum and Raetia. On land the confederation of Goths threaten the lower Danube provinces, and on the sea they threaten the shores of Thracia, Bithynia et Pontus, and Cappadocia. In the eastern provinces, the Sassanid Persians had the previous year defeated a Roman field army at Barballisos, and afterwards plundered the defenseless provinces. This period of time is called today the Crisis of the Third Century.
AD 255: Ma Jun, Chinese mechanical engineer from Cao Wei, invents the south-pointing chariot, a path-finding directional compass vehicle that uses a differential gear, not magnetics.
AD 256: Peace and unity are finally restored in China, with the victories of the Wei Kingdom in the north. The ruling dynasty is worn out by war, and the kingdom is ruled by ministers on their behalf.
AD 259: Emperor Valerian leads an army (70,000 men) to relieve Edessa, besieged by the forces of Persian King Shapur I. An outbreak of a plague kills many legionaries, weakening the Roman position in Syria.
AD 260: Emperor Cao Mao of Former Wei state attempts to lead a coup against the powerful regent Sima Zhao, but he himself is killed before it comes to a confrontation.
AD 263: King Odenathus of Palmyra declares himself ruler of the area west of the River Euphrates and is declared Dux Orientalis by the Roman emperor Gallienus.
AD 265: Sima Zhao, who had been the regent and de facto primary authority of the state of Cao Wei for little over 10 years by this point, passes away, leaving his authority to his eldest son, Sima Yan, who will go on to disestablish the state of Cao Wei in February 266, founding the Jin dynasty.
AD 266: King Odaenathus of Palmyra invades Persia to conquer the capital, Ctesiphon, and twice comes as far as the walls of the Persian capital, but fails to take it. After his victories in the East, he pronounces himself with the title "king of kings".