(flourished c. 20 BC) Greek historian and teacher of rhetoric. Born in Halicarnassus, Caria (Asia Minor), Dionysius went to Rome in 30 BC. His history of Rome, from its origins to the First Punic War, is written from a pro-Roman standpoint but carefully researched. It is, with Livy's, the most valuable source for early Roman history. Its 20 books began to appear in 7 BC; the last 10 have been lost.