Greek historian of the Hellenistic period (Megalopolis, 2nd century BC), expert in political and military affairs. He served as a cavalry officer and, later, as commanding general of the Achaean League, a confederation of city-states from the Peloponnese peninsula. He was one of the nobles of his country who were taken as a hostage to Rome in 167 BC, where he gathered information to write his monumental Histories. Of the 40 original volumes, only the first five are extant. They document the rise of the Roman Republic as the hegemonic power in the Mediterranean, during the period of 264–146 BC, describing in detail the Punic Wars and Macedonian Wars. He also wrote other minor works, nowadays lost, such as the treatise entitled Tactics, on military strategy, and a history of the Numantine War.