Ancient Rome (in Latin, Rome) denotes the unitary political entity resulting from the expansion of the city of Rome, which in its heyday, eventually stretched from Britain to the Sahara Desert and from the Iberian Peninsula to the Euphrates. Initially, after its foundation (according to tradition in 753 a.), Etruscan Rome was a monarchy. Later (509 a.) America was a republic, and in 27 a. C. became an empire. The most glorious period known as Pax Romana, due to the relative state of harmony that prevailed in the regions that were under Roman rule, a period of order and prosperity the Empire met under the Antonine Dynasty (96-192 ) and, to a lesser extent under Severans (193-235). It is a crucial element of the development of the West, and later also in the East.