This article is a good introduction to Xenophon.

The major thing that's missing here is that his writings were actually very influential among ancient philosophers, especially ones of the Stoic school.

For example, Zeno of Citium, who had found the Stoic school, decided to become a philosopher after reading Xenophon's Memorabilia. Epictetus, a prominent philosopher of Roman era, references Xenophon's writing as much as Plato.

I wonder since when philosophy became all about Plato.