This historian was born in Arcadia, son of the general of the Achaean Confederacy, Lykortas. He travelled widely, to Spain, Africa, Gaul, and the Alps, which helped familiarize him with the sites about which he later wrote.
He spent eighteen years in Rome, during the golden age of the republic, and was very impressed by Roman society and values.
His 'Histories' consists of 40 books, though only five have survived. He relates the history of the Greeks and Romans during the period from 220 and 146 BC, and took part personally in many of the events he describes.
A main theme which emerges in this work is his admiration of the Roman political system, which was a mix of oligarchic, democratic and monarchic elements. His work was much acclaimed during his lifetime and was a source for Diodhoros, Plutarch, and Titus Livius, as well as providing a beginning for historians who followed him and who continued his history, such as Poseidonios and Strabo.