The Early Empire The Roman Empire can broadly be divided into two phases, ‘early’ and ‘late’, divided by the third century as a sort of historical watershed between them. In other words, the whole period down to the main part of the third century can be called the ‘early empire’, and the period after that the ‘late empire’. A major difference between the two superpowers and their respective empires was that the Roman Empire was culturally much more diverse than that of Iran. The Parthians and later the Sasanians, the dynasties that ruled Iran in this period, ruled over a population that was largely Iranian.
The Roman Empire, by contrast, was a mosaic of territories and cultures that were chiefly bound together by a common system of government. Many languages were spoken in the empire, but for the purposes of administration Latin and Greek were the most widely used, indeed the only languages. The upper classes of the east spoke and wrote in Greek, those of the west in Latin, and the boundary between these broad language areas ran somewhere across the middle of the Mediterranean, between the African provinces of Tripolitania (which was Latin speaking) and Cyrenaica (Greek-speaking). All those who lived in the empire were subjects of a single ruler, the emperor, regardless of where they lived and what language they spoke.
The regime established by Augustus, the first emperor, in BCE was called the ‘Principate’. Although Augustus was the sole ruler and the only real source of authority, the fiction was kept alive that he was actually only the ‘leading citizen’ ( Princeps in Latin), not the absolute ruler. This was done out of respect for the Senate, the body which had controlled Rome earlier, in the days when it was a Republic.* The Senate had existed in Rome for centuries, and had been and remained a body representing the aristocracy, that is, the wealthiest families of Roman and, later, Italian descent, mainly landowners. Most of the Roman histories that survive in Greek and Latin were written by people from a senatorial background.