Xenophon wrote the Cyropaedia to outline his political and moral philosophy.
He did this by endowing a fictional version of the boyhood of Cyrus the Great,  founder of the first Persian Empire, with the qualities of what Xenophon considered the ideal ruler.
Historians have asked whether Xenophon's portrait of Cyrus was accurate or if Xenophon imbued Cyrus with events from Xenophon's own life.
The consensus is that Cyrus’s career is best outlined in the Histories of Herodotus.
But Steven Hirsch writes, "Yet there are occasions when it can be confirmed from Oriental evidence that Xenophon is correct where Herodotus is wrong or lacks information.
A case in point involves the ancestry of Cyrus."
Herodotus contradicts Xenophon at several other points, most notably in the matter of Cyrus’s relationship with the Median Kingdom.
Herodotus says that Cyrus led a rebellion against his maternal grandfather, Astyages king of Media, and defeated him, thereafter (improbably) keeping Astyages in his court for the remainder of his life (Histories 1.130).
The Medes were thus "reduced to subjection" (1.130) and became "slaves" (1.129) to the Persians 20 years before the capture of Babylon in 539 BC.

The Cyropaedia relates instead that Astyages died and was succeeded by his son Cyaxares II, the maternal uncle of Cyrus (1.5.2).
In the initial campaign against the Lydians, Babylonians and their allies, the Medians were led by Cyaxares and the Persians by Cyrus, who was crown prince of the Persians, since his father was still alive (4.5.17).
 Xenophon relates that at this time the Medes were the strongest of the kingdoms that opposed the Babylonians (1.5.2).
There is an echo of this statement, verifying Xenophon and contradicting Herodotus, in the Harran Stele, a document from the court of Nabonidus.
In the entry for year 14 or 15 of his reign (542-540 BC), Nabonidus speaks of his enemies as the kings of Egypt, the Medes, and the Arabs.
There is no mention of the Persians,
although according to Herodotus and the current consensus the Medians had been made "slaves" of the Persians several years previously.
It does not seem that Nabonidus would be completely misled about who his enemies were, or who was really in control over the Medes and Persians just one to three years before his kingdom fell to their armies.

Other archaeological evidence supporting Xenophon’s picture of a confederation of Medes and Persians, rather than a subjugation of the Medes by the Persians, comes from the bas-reliefs in the stairway at Persepolis.
These show no distinction in official rank or status between the Persian and Median nobility.
Although Olmstead followed the consensus view that Cyrus subjugated the Medes, he nevertheless wrote, "Medes were honored equally with Persians; they were employed in high office and were chosen to lead Persian armies."
A more extensive list of considerations related to the credibility of the Cyropaedia’s picture of the relationship between the Medes and Persians is found on the Cyropaedia page.

Both Herodotus (1.123,214) and Xenophon (1.5.1,2,4, 8.5.20) present Cyrus as about 40 years old when his forces captured Babylon.
In the Nabonidus Chronicle, there is mention of the death of the wife of the king (name not given) within a month after the capture of Babylon.
It has been conjectured that this was Cyrus’s first wife, which lends credibility to the Cyropaedia’s statement (8.5.19) that Cyaxares II gave his daughter in marriage to Cyrus soon (but not immediately) after the fall of the city, with the kingdom of Media as her dowry.
When Cyaxares died about two years later the Median kingdom passed peaceably to Cyrus, so that this would be the true beginning of the Medo-Persian Empire under just one monarch.
Xenophon wrote the Cyropaedia to outline his political and moral philosophy. He did this by endowing a fictional version of the boyhood of Cyrus the Great,  founder of the first Persian Empire, with the qualities of what Xenophon considered the ideal ruler. Historians have asked whether Xenophon's portrait of Cyrus was accurate or if Xenophon imbued Cyrus with events from Xenophon's own life. The consensus is that Cyrus’s career is best outlined in the Histories of Herodotus. But Steven Hirsch writes, "Yet there are occasions when it can be confirmed from Oriental evidence that Xenophon is correct where Herodotus is wrong or lacks information. A case in point involves the ancestry of Cyrus." Herodotus contradicts Xenophon at several other points, most notably in the matter of Cyrus’s relationship with the Median Kingdom. Herodotus says that Cyrus led a rebellion against his maternal grandfather, Astyages king of Media, and defeated him, thereafter (improbably) keeping Astyages in his court for the remainder of his life (Histories 1.130). The Medes were thus "reduced to subjection" (1.130) and became "slaves" (1.129) to the Persians 20 years before the capture of Babylon in 539 BC.
The Cyropaedia relates instead that Astyages died and was succeeded by his son Cyaxares II, the maternal uncle of Cyrus (1.5.2). In the initial campaign against the Lydians, Babylonians and their allies, the Medians were led by Cyaxares and the Persians by Cyrus, who was crown prince of the Persians, since his father was still alive (4.5.17).  Xenophon relates that at this time the Medes were the strongest of the kingdoms that opposed the Babylonians (1.5.2). There is an echo of this statement, verifying Xenophon and contradicting Herodotus, in the Harran Stele, a document from the court of Nabonidus. In the entry for year 14 or 15 of his reign (542-540 BC), Nabonidus speaks of his enemies as the kings of Egypt, the Medes, and the Arabs. There is no mention of the Persians,
although according to Herodotus and the current consensus the Medians had been made "slaves" of the Persians several years previously. It does not seem that Nabonidus would be completely misled about who his enemies were, or who was really in control over the Medes and Persians just one to three years before his kingdom fell to their armies.
Other archaeological evidence supporting Xenophon’s picture of a confederation of Medes and Persians, rather than a subjugation of the Medes by the Persians, comes from the bas-reliefs in the stairway at Persepolis. These show no distinction in official rank or status between the Persian and Median nobility. Although Olmstead followed the consensus view that Cyrus subjugated the Medes, he nevertheless wrote, "Medes were honored equally with Persians; they were employed in high office and were chosen to lead Persian armies." A more extensive list of considerations related to the credibility of the Cyropaedia’s picture of the relationship between the Medes and Persians is found on the Cyropaedia page.
Both Herodotus (1.123,214) and Xenophon (1.5.1,2,4, 8.5.20) present Cyrus as about 40 years old when his forces captured Babylon. In the Nabonidus Chronicle, there is mention of the death of the wife of the king (name not given) within a month after the capture of Babylon. It has been conjectured that this was Cyrus’s first wife, which lends credibility to the Cyropaedia’s statement (8.5.19) that Cyaxares II gave his daughter in marriage to Cyrus soon (but not immediately) after the fall of the city, with the kingdom of Media as her dowry. When Cyaxares died about two years later the Median kingdom passed peaceably to Cyrus, so that this would be the true beginning of the Medo-Persian Empire under just one monarch.
Xenophon