History of the Roman Empire 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. In the view of the Greek historian Dio Cassius, a contemporary observer, the accession of the emperor Commodus in 180 AD 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. In 212, during the reign of Caracalla, Roman citizenship was granted
Historiography of the fall of the Western Roman Empire Empire of Late Antiquity already looked very different from classical Rome. The Roman Empire emerged from the Roman Republic when Julius Caesar and Augustus Caesar transformed it from a republic into a monarchy. Rome reached its zenith in the 2nd century, then fortunes slowly declined (with many revivals and restorations along the way). The reasons for the decline of the Empire are still debated today, and are likely multiple. Historians infer that the population appears to have diminished in many provinces—especially western Europe—from the diminishing size of fortifications built to protect the cities from barbarian incursions from the 3rd century