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 argues that the severe fall in population left the state apparatus and army too large for the population to support, leading to further economic and social decline that eventually killed the Western Empire. The Eastern half survived due to its larger population, which even after the plagues was sufficient for an effective state apparatus. Archaeology has revealed that from the 2nd century onward, the inhabited area in most Roman towns and cities grew smaller and smaller. Imperial laws concerning "agri deserti", or deserted lands, became increasingly common and desperate. The economic collapse of the 3rd century may also be evidence