and the fragmentation of his empire, which was at this time divided among the Diadochi. Hellenistic period (323–146 BC) Classical Greece entered the Hellenistic period with the rise of Macedon and the conquests of Alexander the Great. Greek became the lingua franca far beyond Greece itself, and Hellenistic culture interacted with the cultures of Persia, the Kingdom of Israel and Kingdom of Judah, Central Asia and Egypt. Significant advances were made in the sciences (geography, astronomy, mathematics, etc.), notably with the followers of Aristotle (Aristotelianism). The Hellenistic period ended with the rise of the Roman Republic to a super-regional power in the 2nd century BC and the Roman conquest of Greece in 146 BC. Roman Republic (5th to 1st centuries BC) The Republican period of Ancient Rome began with the overthrow of the Monarchy c. 509 BC and lasted over 450 years until its subversion through a series of civil wars, into the Principate form of government and the Imperial period. During the half millennium of the Republic, Rome rose from a regional power of the Latium to the dominant force in Italy and beyond. The unification of Italy under Roman hegemony was a gradual process, brought about in a series of conflicts of the 4th and 3rd centuries, the Samnite Wars, Latin War, and Pyrrhic War. Roman victory in the Punic Wars and Macedonian Wars established Rome as a super-regional power by the 2nd century BC, followed up by the acquisition of Greece and Asia Minor. This tremendous increase of power was accompanied by economic instability and social unrest, leading to the Catiline conspiracy, the Social War and the First Triumvirate, and finally the transformation to the Roman Empire in the latter half of the 1st century BC. Roman Empire (1st century BC to 5th century AD) The precise end of the Republic is disputed by modern historians; Roman citizens of the time did not recognize that the Republic had ceased to exist. The early Julio-Claudian Emperors maintained that the res publica still existed, albeit under the protection of their extraordinary powers, and would eventually return to its full Republican form. The Roman state continued to call itself a res publica as long as it continued to use Latin as its official language. Rome acquired imperial character de facto from the 130s BC with the acquisition of Cisalpine Gaul, Illyria, Greece and Hispania, and definitely with the addition of