From the Internet:
"Xenophon the Athenian was born 431 B.C. He was a pupil of Socrates. He marched with the Spartans, and was exiled from Athens. Sparta gave him land and property in Scillus, where he lived for many years before having to move once more, to settle in Corinth. He died in 354 B.C.

The Anabasis is his story of the march to Persia to aid Cyrus, who enlisted Greek help to try and take the throne from Artaxerxes, and the ensuing return of the Greeks, in which Xenophon played a leading role. This occurred between 401 B.C. and March 399 B.C. "