The origins of the decline go back at least to Augustus’ s seizure of power, which set in motion changes that made political institutions much more extractive. These included changes in the structure of the army, which made secession impossible, thus removing a crucial element that ensured political representation for common Romans. The emperor Tiberius, who followed Augustus in AD 14, abolished the Plebeian Assembly and transferred its powers to the Senate. Instead of a political voice, Roman citizens now had free handouts of wheat and, subsequently, olive oil, wine, and pork, and were kept entertained by circuses and gladiatorial contests. With Augustus’ s reforms, emperors began to rely not so much on the army made up of citizen-soldiers, but on the Praetorian Guard, the elite group of professional soldiers created by Augustus. The Guard itself would soon become an important independent broker of who would become emperor, often through not peaceful means but civil wars and intrigue. Augustus also strengthened the aristocracy against common Roman citizens, and the growing inequality that had underpinned the conflict between Tiberius Gracchus and the aristocrats continued, perhaps even strengthened.
The accumulation of power at the center made the property rights of common Romans less secure. State lands also expanded with the empire as a consequence of confiscation, and grew to as much as half of the land in many parts of the empire. Property rights became particularly unstable because of the concentration of power in the hands of the emperor and his entourage. In a pattern not too different from what happened in the Maya citystates, infighting to take control of this powerful position increased. Civil wars became a regular occurrence, even before the chaotic fifth century, when the barbarians ruled supreme. For example, Septimius Severus seized power from Didius Julianus, who had made himself emperor after the murder of Pertinax in AD 193. Severus, the third emperor in the so-called Year of the Five Emperors, then waged war against his rival claimants, the generals Pescennius Niger and Clodius Albinus, who were finally defeated i n AD 194 and 197, respectively. Severus confiscated all the property of his losing opponents in the