DIO CASSIUS (more correctly, Cassius Dio; b. Nicea, Bithynia, ca. 160, d. Nicea, after 229), Roman official whose Rhomaikē Historia (ed. U. P. Boissevain, 3 vols., Berlin, 1896-1901) is important for the study of Parthian history. He was the son of a government official under Marcus Aurelius and during the reign of Commodus (180-93) went to Rome, where he began his public career. Under Septimius Severus (193-211) he was named pretorius (193) and consul (ca. 211). He accompanied Caracalla (211-17) on his campaign to Armenia in 216, remaining in the east for several years, and under Severus Alexander (222-35) he was proconsul of Africa, then of Dalmatia and Upper Pannonia (225-28), and in 229 consul again. He soon retired from public life, however, and returned to his native land, where he remained for the rest of his days (Prosopographia; Gabba, pp. 289 ff.).

At the age of forty years he settled in Capua, in order to prepare himself to write his history. By his own report (72.23), he spent ten years assembling his materials and the next twelve writing his text, up to the death of Septimius Severus; the rest of the work must have been completed under Severus Alexander (Christ et al., pp. 796-97). The work originally consisted of eighty books, beginning with the arrival of Aeneas in Rome and ending in the year 229 C.E. Only books 36-60 have been completely preserved; they contain the history of the years 68 B.C.E. to 47 C.E., a critical period in Roman relations with the Parthians. For the subsequent years only extracts from an 11th-century epitome prepared by the Byzantine Joannes Xiphilinus survive (Ziegler, 1964, pp. 73 ff.); books 1-35 were already missing from the manuscript consulted by Xiphilinus, but in the following century they were known to another Byzantine historian, Joannes Zonaras, who drew upon them for books 7-12 of his Chronicle (von Gutschmid, pp. 549-62; Schwartz; Boissevain’s preface to vol. III, pp. iii-xiii; Christ et al., pp. 795-99). It should be noted that in the Suda (II, pp. 116-17) the Persica by Dinon of Colophon is mistakenly attributed to Dio.

Dio described contemporary personalities and events at first hand or from official documents; his history is thus the principal source on the Roman campaign against the Parthians in 197-99 (76 (75.9-11); Debevoise, pp. 256 ff.), during which Seleucia, Babylon, and Ctesiphon were captured and Septimius Severus then unsuccessfully laid siege to Hatra twice in a period of several months (76 (75.10-12); Rubin, pp. 421 ff., who expresses unfounded doubts about the truth of Dio’s unique account). Dio is also the sole reliable, athough succinct, source on the campaign of Caracalla (78 (77.12.12). Before his final retirement to Bithynia he recorded the defeat of the Parthians by the Sasanian Ardašīr I in 224, emphasizing the danger of Ardašīr’s having established a foothold in Mesopotamia and Syria and his threat to reconquer all the territory that had formerly belonged to Persian empire (80. 3-4). In several places in the history Parthians are mentioned as if they were still in power, suggesting that Dio did not revise his text after the fall of the Arsacids (Hartmann, pp. 75 ff.; Millar, pp. 30, 177, 206).

It is not always easy to identify Dio’s sources for periods before his lifetime. Books 36 and 37 (abridged by Xiphilinus) were based mainly on Sallust’s Histories (Reinach, pp. 449-51), but recent research has revealed that the work of the Alexandrine historian Timagenes (2nd half of the 1st century B.C.E.), who was partial to the Parthians, may also have been used (Clementini). For the more detailed account of Crassus’ Parthian campaigns in Book 40, containing information not in Plutarch’s parallel account, Dio’s principal source was the Roman History of Livy, and he also drew on Arrian’s Parthica (Hartmann, pp. 74 ff.). The account of the nine-month journey to Rome of the Parthian Tiridates, brother of Balāš I (ca. 51-80), and his coronation as king of Armenia by the emperor Nero deserve special attention (63.1-7; cf. Cumont, pp. 145-54; Lemosse, pp. 462 ff.) as an important contribution to the history of the relations among the Parthians, Rome, and Armenia after the agreement of Rhandeia in 63 C.E., providing detail that is lacking in the works of Tacitus and Suetonius. For Trajan’s Parthian war (68.17-31; cf. Longden, pp. 1-35; Debevoise, pp. 213-39) Dio relied largely on Arrian’s Parthica, which he consulted in the original (fragments ed. by Roos and Wirth, Leipzig, 1968, pp. 205-24; cf. see Roos, pp. 30 ff., esp. pp. 38-39; Hartmann, pp. 82 ff.).



R. Adinolfi, in Puteoli 3, 1979, pp. 35-40.

G. Alföldy, in Theinisches Museum 114, 1971, pp. 360-68.

W. von Christ, W. Schmid, and O. Stählin, Geschichte der griechischen Literatur, 6th ed., II/2, Munich, 1924.

G. Clementini, in Invigiliata Lucernis 7-8, 1985-86, pp. 141-60.

F. Cumont, in Rivista di filologia, N.S. 11, 1936, pp. 147-51.

N. C. Debevoise, A Political History of Parthia, Chicago, 1969.

E. Gabba, “Sulla storia romana di Cassio Dione,” Rivista storica italiana 6, 1955.

A. von Gutschmid, Kleine Schriften VI, Leipzig, 1891. K. Hartmann, in Philologus 74, 1917, pp. 73-91.

M. Lemosse, “Le couronnement de Tiridate,” in Mélanges en l’honneur de Gilbert Gidel, Paris, 1961, pp. 455-58.

R. P. Longdon, in Journal of Roman Studies 21, 1931, p. 135.

F. Millar, A Study of Dio Cassius, Oxford, 1964.

Prosopographia Imperii Romani II2, 1936, pp. 115-17.

T. Reinach, Mithridate Eupator, roi du Pont, Paris, 1890.

A. G. Roos, Studia Arrianea, Leipzig, 1912.

Z. Rubin, in Chiron 5, 1975, pp. 419-41.

E. Schwartz, “Cassius 40,” in Pauly-Wissowa, cols. 1684-722.

A. Stepanian, in Revude des études arméniennes 11, 1975, pp. 216-18.

Suda, ed. A. Adler, Leipzig, 1928-38.

K. H. Ziegler, Die Beziehungen zwischen Rom und dem Partherreich, Wiesbaden, 1964.

Idem, “Xiphi-linos,” in Pauly-Wissowa IXA/2, cols. 2132-34.

(Marie Louise Chaumont)

Originally Published: December 15, 1995

Last Updated: November 28, 2011

This article is available in print.
Vol. VII, Fasc. 4, pp. 420-421