The empire ruled by Augustus Caesar was the Roman Empire. Augustus, originally named Gaius Octavius, became the first emperor of Rome after the defeat of Mark Antony and Cleopatra in 30 BCE and the subsequent establishment of the principate. His reign (27 BCE to 14 CE) marked the transition from a republic to an empire, implementing a range of reforms that stabilized and expanded Roman territory, economy, and culture. Augustus initiated the Pax Romana, a long period of relative peace and prosperity, which fostered trade, infrastructure development, and the flourishing of arts and literature, significantly shaping the future of the empire.