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 to the fall of the West Roman Empire (395-476), in his book "The Fall of the West: The Slow Death of the Roman Superpower" (2009). William H. McNeill, a world historian, noted in chapter three of his book "Plagues and Peoples" (1976) that the Roman Empire suffered the severe and protracted Antonine Plague starting around 165 AD. For about twenty years, waves of one or more diseases, possibly the first epidemics of smallpox and measles, swept through the Empire, ultimately killing about half the population. Similar epidemics, such as the Plague of Cyprian, also occurred in the 3rd century. McNeill