Rome--A Vast & Powerful Empire Rome was at the peak of its power from the beginning of Augustus' rule in 27 B.C.E. to 180 B.C.E. For 207 years, peace reigned throughout the empire, except for some fighting with tribes along the borders. This period of peace and prosperity is known as the Pax Romana—Roman peace. During this time, the Roman Empire included more than 3 million square miles. Its population numbered between 60 and 80 million people. About one million people lived in the city of Rome itself.