Cyaxares II () was a king of the Medes whose reign is described by the Greek historian Xenophon. Some theories have equated this figure with the "Darius the Mede" named in the Book of Daniel. He is not mentioned in the histories of Herodotus or Ctesias, and many scholars doubt that he actually existed. The question of his existence impacts on whether the kingdom of the Medes merged peacefully with that of the Persians in about 537 BC, as narrated by Xenophon (8.6.22, 8.7.1), or was subjugated in the rebellion of the Persians against Cyrus' grandfather in 559 BC, a date derived from Herodotus (1.214) and almost universally accepted by current scholarship.

Xenophon’s Cyropaedia According to Xenophon's Cyropaedia (1.5.2), Cyaxares II became king after Astyages to the throne of the Median Empire, and he was also the brother of Mandane, Cyrus the Great's mother (1.2.1, 1.4.7). He describes the Persian, Cyrus II/The Great, as leading the campaign to conquer Babylon in 539 BC, while his uncle, Cyaxares II, remained in Ecbatana.Cyropaedia 6.3.2, 7.4.16, 8.5.17. Cyaxares II was by then an old man,Cyropaedia 4.5.32, 6.1.6. and because Cyrus II/The Great was in command of the campaign, the army came to regard Cyrus the Great as king. After Cyrus II/The Great invited Cyaxares (II) to a palace he had prepared for him in Babylon, Cyaxares (II) granted him his daughter (Cyrus II/The Great's first cousin) in marriage, with the Median kingdom as her dowry.Cyropaedia 8.5.19. On the assumption that Cyaxares II is Darius the Mede, it is claimed that he nominally reigned from Babylon as head of the Medo-Persian empire for two years until his death, the real power being Cyrus II/The Great's. Upon the death of Cyaxares II, the empire passed peaceably to Cyrus II/The Great.

Controversy about name Friedrich König claimed that Xenophon was confused about Cyaxares (II) because this was the name of the father of Astyages (Cyaxares I). However, it was not unusual, especially among kings, for an individual to have the same name as his grandfather. This was the case with both Cyrus the GreatHerodotus 1.111; Cyrus Cylinder (Pritchard, p. 316). and Cambyses II.Herodotus 1.111; Cyropaedia 1.2.1, 8.7.11; Cyrus Cylinder (Pritchard, p. 316). Darius (I) Hystaspes had a grandson named Darius who was heir apparent but was killed before he could become king.

Debate about existence of Cyaxares II Cyaxares II figures prominently in Xenophon’s Cyropaedia. In contrast, he is absent from the Histories of Herodotus, which leaves no place for Cyaxares II. Herodotus says the Median king Astyages had no son, and that his successor as king of both Media and Persia was Cyrus the Great. The modern consensus of historians agrees with Herodotus. John Whitcomb wrote that Xenophon's Cyaxares II "was a mere figment of the imagination."

From at least the time of JeromeGleason L. Archer, Jr., ed. and trans., Jerome’s Commentary on Daniel (Grand Rapids: Baker, 1958), p. 55. until the 19th century, many writers, both Jewish and Christian, accepted the existence of Cyaxares II. He was regarded as the king of Media at the end of the Neo-Babylonian Empire in the biblical commentaries of John Calvin, Adam Clarke, Keil and Delitzsch, and Lange. In Lange's commentary, Otto Zöckler named Gesenius, Hengestenberg, and other more recent writers who equated Cyaxares II with Daniel's Darius the Mede.Otto Zöckler, “The Book of the Prophet Daniel” in John Peter Lange, Commentary on the Holy Scriptures: Critical, Doctrinal, and Ethical, tr. Philip Schaff (Grand Rapids: Zondervan, 1960) Vol. 7, p. 36. These commentaries noted similarities between Cyaxares II as portrayed by Xenophon and what may be inferred about Darius the Mede from the sparse statements about him in the Book of Daniel. In their view, the difference in name could be explained by the fact that kings at that time—including Artaxerxes I, Darius II, Artaxerxes III, and Darius III—had a throne name in addition to their personal name. In the case of Cyaxares II, Harpocration and Berossus were cited as evidence showing that the throne name of Cyaxares II was Darius the Mede.Johann F. K. Keil, in Keil and Delitzsch Old Testament Commentaries (Grand Rapids: Associated Publishers and Authors, n.d.), Vol. 6, p. 542.Zöckler in Lange’s Commentary, p. 36. Regarding correlations between Cyaxares II and Darius the Mede, Zöckler wrote, "the account given by Xenophon regarding Cyaxares II so fully agrees with the narrative of Daniel regarding Darius the Mede, that, as Hitzig confesses, 'the identity of the two is beyond a doubt.'"Keil in Keil and Delitzsch, p. 542.

Supporting evidence The following sources generally support, in one way or another, the existence of Cyaxares II as a monarch who succeeded Astyages on the throne of Media, and who continued until sometime shortly after the capture of Babylon by the combined Median and Persian armies and their allies. The sources are listed in chronological order of their composition, with the oldest first.

The Harran Stele The Harran Stele (Pritchard, pp. 362–63) was composed in the fourteenth or fifteenth year of Nabonidus, i.e. 542 to 540 BC, commemorating his restoration of the temple at Ehulhul. Nabonidus relates how, in the tenth year of his reign (546 or 545 BC), hostile kings invited him to return to Babylon. The kings are named as "the kings of the land of Egypt, of the land [v.l. for KUR: URU, of the city] of the Medes, of the land of the Arabs, and all the kings of hostile (lands)". The significance of this lies in its date, just one to three years before Nabonidus lost his kingdom to the Medes and Persians.Beaulieu, Reign of Nabonidus p. 143. The fall of Babylon to the Medes and Persians is universally accepted as occurring in 539 BC, three years or less after Beaulieu’s date for the Harran Stele. It was also some 13 or 14 years after Cyrus had supposedly subjugated the Medes and became ruler of the combined empire in 559 B.C. according to Herodotus and the consensus of modern historians who follow him. Nabonidus makes no mention of the Persians who soon would be the leaders of those who captured his capital. This is consistent with Xenophon's picture of the Persians still being the subordinate partner in the Medo-Persian confederacy at the time, with Cyrus the junior sovereign under his uncle, Cyaxares II king of Media.Cyropaedia 3.3.24–25, 4.1.19–21, 8.5.17–19, esp. 19. Nowhere in any surviving inscription is Cyrus called the king of Media, unless it is maintained that the present inscription is interpreted that way;It would be circular reasoning to say that the Harran Stele shows that Cyrus is called the King of the Medes because the Medes are listed on the Harran Stele as the enemy of the Babylonians. this would be in contradiction to other sources where Cyrus is referred to "king of Anshan", "king of Persia", "the great king" and other similar titles. The Harran Stele therefore is evidence that just shortly before the fall of Babylon, the king of the Medes, whose name is not given, not only existed but was considered a more important enemy of the Babylonians than Cyrus and the Persians.In the Harran Stele (Pritchard, 562b), Nabonidus lists his principal enemies of the Babylonians as the Egyptians, Medes, and Arabs; the Persians are not mentioned.

The Persepolis Reliefs

Construction of the Persian city of Persepolis began early in the reign of Darius I (522–486 BC), probably about 515 BC, and construction was completed in the reign of his son Xerxes (486–465 BC). The great staircase of the Apadana was part of the first building phase. Reliefs on part of the staircase depict Persian and Median nobles, with no apparent distinction of rank.Yamauchi, Persia and the Bible, "The northern part of the eastern staircase depicts alternating Persian and Median nobles conversing with each other." p. 347. Depiction of Persians and Medians as equals is not consistent with Herodotus' account that the Persians "subjugated" and made "slaves" of the Medes about 20 years before the fall of Babylon (Histories 1.129,130). They are consistent with the picture presented in the Cyropaedia of a confederation between the two nations, with the Medes initially being the senior partners in the confederacy.

Aeschylus in The Persians Aeschylus' tragedy, The Persians, was written in 472 BC. The author, Aeschylus, was a contemporary of Darius Hystaspes (522–486 BC) and his son Xerxes (486–465). He fought the Persians at Marathon and Salamis. The Persians predates both Xenophon and Herodotus, and is therefore independent of either of those sources. The tragedy is a dramatic reenactment of the Persian defeat at Salamis (486 BC). In it, the ghost of Darius I describes the two Median kings who preceded Cyrus as rulers of the Medo-Persian alliance: For the Mede was the first leader of [our] host;And another, his son, completed this work,For [his] mind directed his passion.And third from him was Cyrus, a fortunate man;When he ruled, he established peace for all his own. In Herodotus' history, the two Median kings who preceded Cyrus were Cyaxares I and his son Astyages. But also according to Herodotus, Cyaxares I did not establish a Medo-Persian confederacy, and Astyages did not "complete this work"; instead he lost his throne after initiating a war against Cyrus. The conflict of Aeschylus with Herodotus regarding the basic history of the Medes and Persians is so obvious that Walther Kranz stated, "Certainly one could complain, that thus Aeschylus (like his hearers) knew nothing about the enormous revolution in the East regarding the changeover of the dominion to the Persians." Steven Anderson writes, "The attempt to reconcile Aeschylus with Herodotus thus breaks down, not only because of the problem of correlating the Median kings, but also because of the problem of a Medo-Persian confederacy. Aeschylus presents the Medes and Persians as a united host right from the first Median king in the list, and does not indicate that there was a violent conquest of Media by Cyrus, as Herodotus claims there was."

In the past, the interpretation taken by many classicists was that the two Median kings preceding Cyrus in this reference were Astyages and Xenophon's Cyaxares II. This was the position of Thomas Stanley, who edited what became the standard edition of the works of Aeschylus from the seventeenth to the nineteenth centuries. That the Medes under Astyages began a confederacy with the Persians, as indicated by Aeschylus, is evidenced by Astyages giving his daughter Mandane in marriage to Cambyses, the father of Cyrus by Mandane. This marriage alliance is attested in the histories of both Herodotus and Xenophon. "In the ancient Near Eastern context, such marriages signified the formation of political alliances, and it seems that Astyages made just such an alliance with Persia with a view toward checking Babylonian hegemony. The work which he began of opposing Babylonian hegemony through the confederation with Persia was completed by his son Darius/Cyaxares II, who occupied the Median throne when Babylon fell to the Medo-Persian army."Anderson Darius the Mede: A Reappraisal, p. 117. Aeschylus in these few lines presents a picture of the early days of the Medo-Persian confederacy that is in harmony with Xenophon's succession of Median kings, including Cyaxares II.

Xenophon in the Cyropaedia

Xenophon was a mercenary soldier who fought in the Persian civil war between Cyrus the Younger and his brother Artaxerxes II of Persia. The story of the 10,000 Greek mercenaries is related in Xenophon's most famous work, the Anabasis. Xenophon fought on the side of Cyrus and greatly admired him. After Cyrus was slain, Xenophon became leader of the Greeks in their long trek out of the territory controlled by the Persians. Since he apparently was quite familiar with the younger Cyrus and his attendants, he had ample opportunity to learn the court remembrances of Cyrus the Great.