Pax Romana, meaning 'Roman Peace' in Latin, was the period of relative stability and peace that started with the reign of the Emperor Augustus in 27 BC and lasted roughly 207 years, ending with the death of the Emperor Marcus Aurelius in 180 AD. Augustus established Pax Romana (which is sometimes called Pax Augusta) after he defeated Mark Antony at the Battle of Actium in the Last War of the Roman Republic in 30 BC.
While Rome and its empire still saw the occasional conflict and civil war (such as the year of the four emperors in 69 AD) it was nothing like the wars and bloodshed it had faced during the last decades of the Roman Republic, which saw Rome facing enemies on all fronts, and a series of bloody civil wars that left it devastated and longing for change – ultimately resulting in the transition from an oligarchic republic to an autocratic hegemony.
This change in structure allowed the unified and steadfast Roman Empire to expand rapidly in territory, influence and population. The empire reached its greatest territorial extent between 98-117 AD during the reign of the Emperor Trajan, while the population swelled to 70 million – which was estimated to be roughly one third of the entire world population at the time.
Rome was able to fund it's expansion through the taxation of newly acquired provinces which had no choice but to recognise Roman authority, but they in turn received protection and peacekeeping from the Roman military. Augustus reintroduced the census of the Roman Empire to determine how much citizens and landowners owed in tax. The more provinces that fell under Roman rule increased the taxes and natural resources flowing towards Rome, as well as more man power for the army. Any revolts that did arise during the time of Pax Romana were easily dealt with due to the power of the military who remained loyal to the emperors. Most provinces ultimately saw the benefits of being part of the Roman Empire, and uprisings during this time were few and far between.
Ever expanding territory also meant that the empire was becoming too large for one ruler, and during the reign of Marcus Aurelius he opted to co-rule with Lucius Verus and later with his son, Commodus. This helped to set a standard that would endure until the fall of the Roman Empire, and following this it would now become common for two or more emperors to exist at any one time.
Pax Romana ended with the reign of Commodus in 180 AD which saw an increase in threats from foreign nations and within the empire itself, culminating in crisis of the third century. The contemporary historian and politician Cassius Dio remarked that Commodus' reign took Rome 'from a kingdom of gold to one of iron and rust'.