In the view of the Greek historian Dio Cassius, a contemporary observer, the accession of the emperor Commodus in AD 180 marked the descent 'from a kingdom of gold to one of rust and iron' -a famous comment which has led some historians, notably Edward Gibbon, to take Commodus' reign as the beginning of the decline of the Roman Empire. Vespasian became the founder of the brief Flavian dynasty, to be followed by the Nerva–Antonine dynasty which produced the ' Five Good Emperors': Nerva, Trajan, Hadrian, Antoninus Pius and the philosophically inclined Marcus Aurelius. The success of Augustus in establishing principles of dynastic succession was limited by his outliving a number of talented potential heirs the Julio-Claudian dynasty lasted for four more emperors- Tiberius, Caligula, Claudius, and Nero-before it yielded in AD 69 to the strife-torn Year of the Four Emperors, from which Vespasian emerged as victor. Subsequent emperors all took this name as the imperial title Augustus. In 27 BC, the Senate made Octavian imperator ('commander') thus beginning the Principate, the first epoch of Roman imperial history usually dated from 27 BC to AD 284 they later awarded him the name Augustus, 'the venerated'. Antony was defeated at the Battle of Actium in 31 BC. Civil war engulfed the Roman state in the mid 1st century BC, first between Julius Caesar and Pompey, and finally between Octavian and Mark Antony. Rome had begun expanding shortly after the founding of the Roman Republic in the 6th century BC, though it did not expand outside the Italian Peninsula until the 3rd century BC.

Ancient Rome became a territorial empire while still a republic, but was then ruled by Roman emperors beginning with Augustus ( r. 27 BC – AD 14), becoming the Roman Empire following the death of the last republican dictator, the first emperor's adoptive father Julius Caesar. The history of the Roman Empire covers the history of ancient Rome from the fall of the Roman Republic in 27 BC until the abdication of Romulus Augustulus in AD 476 in the West, and the Fall of Constantinople in the East in AD 1453. Territorial development of the Roman Republic and of the Roman Empire (Animated map)

Roman empire timelime