The Roman Republic was established in 509 BC and expanded through military conquests like the Punic Wars against Carthage between 264-146 BC. This granted Rome control of the Mediterranean and led to the transition from republic to empire under rulers like Julius Caesar and Augustus. The Pax Romana period between 27 BC to 180 AD brought peace and prosperity to the Roman Empire under the rule of the Five Good Emperors and a link between government and traditional Roman religion.