Artaxerxes II had a Greek doctor, Ctesias, who wrote a Persian history that mentions Cyrus the Younger's campaign. It is extremely fragmentary. Here is a translation of the relevant fragmentary. It's preserved in Photius, a Byzantine Patriarch. The fragment notes Cyrus brought Greeks and names Clearchus as the Greek general, and claims Ataxerxes reached an arrangement with the Greeks. No mention of Xenophon in the fragment.

(63) Cyrus revolted from his brother and assembled an army mixed of Greeks and barbarians with Clearchus as the general of the Greeks. Ctesias describes how Syennesis entered into an alliance with both Cyrus and Artaxerxes and how each man advised his own army. Clearchus, the Spartan who led the Greeks, and Menon the Thessalian, both allies of Cyrus, were always at odds with each other because Cyrus always deliberated with Clearchus while he did not rely on Menon at all. Many men deserted from Artaxerxes to Cyrus but no one deserted from Cyrus to Artaxerxes; consequently, Arbarios intended to join Cyrus but was betrayed and thrown into the ashes. (64) Cyrus attacked the king's army, won a victory, but died in the battle when he failed to follow the advice of Clearchus. His body was mutilated by his brother Artaxerxes, who cut off his head and the hand which he used to wound the king and paraded around with them. (65) Clearchus the Spartan retreated with his Greek contingent during the night and occupied one of the cities under Parysatis' dominion. Finally, the king concluded a peace with the Greeks.

Xenophon occasionally cites a man called Ktesias, the personal physician to the Persian king Artaxerxes II, who apparently wrote a history of Persia up to the present day. However, his books, the Indica on India and the Persika on Persia, have not survived in anything other than fragmentary form. The ancients, however, would have had something to corroborate Xenophon's account with.

Corroborate as to what?