Appian of Alexandria was a Greek historian with Roman citizenship who flourished during the reigns of Emperors of Rome Trajan, Hadrian, and Antoninus Pius. His principal surviving work known in Latin as Historia Romana and in English as Roman History was written in Greek in 24 books, before 165. This work more closely resembles a series of monographs than a connected history. It gives an account of various peoples and countries from the earliest times down to their incorporation into the Roman Empire, and survives in complete books and considerable fragments. The work is very valuable, especially for the period of the civil wars. Despite the lack of cited sources for his works, these books of the Roman History are the only extant comprehensive description of these momentous decades of Roman history.