Polybius (/pəˈlɪbiəs/; Greek: Πολύβιος, Polýbios; c. 200 – c. 118 BC) was a Greek historian of the Hellenistic Period noted for his work, The Histories, which covered the period of 264–146 BC in detail. The work describes the rise of the Roman Republic to 'world power' (i.e. domination over the Mediterranean world). Polybius is also renowned for his ideas concerning the separation of powers in government, later used in Montesquieu's The Spirit of the Laws and in the drafting of the United States Constitution.Polybius was born in Arcadia around 200 BC. He was the son of Lycortas, a Greek politician who became Cavalry Commander of the Achaean League. His father's opposition to Roman control of Macedonia resulted in his imprisonment. Polybius was then deported to Rome, where Lucius Aemilius Paulus employed him to tutor his two sons.Polybius had the opportunity to return to Macedonia in 152 BC; he elected to stay, however, in Rome, as by that time he had placed his allegiance in the Roman Republic. He became a close friend of the Roman military commander Scipio Aemilianus, accompanying the general to Hispania and Africa. He was also among the members of the Scipionic Circle. Polybius's The Histories provides a detailed account of Rome's ascent to empire and included his eyewitness account of the Sack of Carthage in 146 BC. Polybius held that historians should only chronicle events whose participants the historian was able to interview, and was among the first to champion the notion of having factual integrity in historical writing, while avoiding bias.