The final century or so of Ptolemaic rule from Alexandria is a sad one, primarily because many of the later Ptolemies, Pharaohs they might have appeared to be, were mere puppets of the Roman Empire. With the death of Cleopatra VII, the last of the Ptolemies to rule, and the defeat of the once-mighty Ptolemaic navy at Actium, in 31 BC Egypt became part of the Roman Empire under Augustus Caesar. Military garrisons were stationed at Alexandria to keep the peace in Egypt, and no doubt to keep a close eye on the Alexandrian Mob, which had not diminished over the years, but had stayed very much alive, and would continue to thrive under the Roman dominion.
The Ptolemies had succeeded in assimilating the Egyptian culture and thus the respect of the native population, but the new Roman rulers who came after them made little attempt to do so. Certainly they adopted the pharaonic titles and built temples in the traditional style, but as Egypt was now ruled in absentia from Rome, the native population, still deeply rooted in their ancient religion and beliefs, refused to honor rulers who no longer performed the ceremonial roles of divine kingship. Indeed, few of the emperors ever set foot in Egypt, let alone Alexandria, until the famed riots of AD 250. Yet the foundations for knowledge laid by the Ptolemies centuries before allowed the city to continue prospering. The first-century AD scientist Hero, who produced works on everything from steam power to the construction of artillery, was a citizen of Alexandria, and the great physician Galen of Pergamum was educated in Alexandria’s famed medical academies. Additionally, a new tradition in learning had begun in Alexandria during the final years of the Ptolemies — philosophy. One of the reasons for the new surge in philosophy was that due to Mithradates of Pontus’ first war against Rome caused many philosophers to leave Athens, and more than a few of them came to settle in Alexandria. It has been said that Augustus Caesar, who was called Octavian at the time, spared Alexandria during his Egyptian campaign largely as a favor to his friend, the philosopher Arius Didymus. Also a citizen of Alexandria was the prolific Jewish author Philo. A member of a wealthy Alexandrian family, Philo was a student of both Platonic philosophy and the Jewish tradition, and he applied one to the other, often with astonishing results. The effects of Greek thought on the early Christian church are largely a result of Philo and other Jewish scholars educated in the Greek tradition of Alexandria.
The end of the Roman Era and the beginning of what is called the Byzantine Era is actually quite difficult to pin down, but certainly the high empire of Rome was in decline. A rapid succession of emperors destroyed any hope of stability, with the exception of the twenty-year reign of emperor Diocletian, who stabilized the money supply (all of the Roman Empire now used one coinage, even Alexandria, which up until now had minted its own money) and made great efforts to reorganize the bureaucracy. Rome was falling, and with it the Empire. An emperor was needed who could protect the Empire from outside invasion as well as repair the internal strife between the various factions, religions, and cliques, all of which were represented in Alexandria. Rome found what it needed, though perhaps not exactly what it wanted in Constantine.