It's clear from reading Xenophon's Anabasis that the Greeks regard themselves as culturally superior to the Persians. Even though the Persians have a rich, ancient civilization of their own, the Greeks cannot respect them as equals. In any case, the Greeks, far from home and feeling increasingly trapped in a foreign land, are not particularly amenable to respecting their opponents. They haven't embarked upon their epic journey to sample the cultural delights of Persia, but to do a job of work before returning home. Such is the life of a mercenary.
For the Greeks, the indigenous peoples of the land they're invading are decidedly "Other." In one particularly revealing passage, this attitude is on full display when the Greeks try to overcome their fear of being trapped by impassable rivers by recalling that supposedly lesser races have been able to overcome such topographical limitations to build prosperous cities:
For we know that the Mysians, whom we should not admit to be better men than ourselves, inhabit many large and prosperous cities in the King's territory, we know that the same is true of the Pisidians, and as for the Lycaonians we even saw with our own eyes that they had seized the strongholds in the plains and were reaping for themselves the lands of these Persians; so, in our case, my own view would be that we ought not yet to let it be seen that we have set out for home; we ought, rather, to be making our arrangements as if we intended to settle here.
If even the Mysians, Pisidians, and Lycaonians can establish themselves in such a hostile environment, then why can't the allegedly superior Greeks?
Though these races are subjects of the Persians rather than actual Persians, the superior attitude adopted towards them by the invading Greeks reflects how they regard the Persians themselves. More evidence of othering comes when Xenophon paints an exotic, and somewhat unflattering, picture of Persian civilization:
I really fear, however, that if we once learn to live in idleness and luxury, and to consort with the tall and beautiful women and maidens of these Medes and Persians, we may, like the Lotus Eaters, forget our homeward way.
The Persians are presented here as being thoroughly steeped in a mire of enervating luxury, their women little more than alluring temptresses who use their beauty as a weapon to seduce unsuspecting Greek warriors and prevent them from returning home. In contrast to Greek civilization, which is given to us throughout Anabasis as embodying traditional male virtues such as courage, endurance, and physical strength, Persian civilization is portrayed by Xenophon as effete, weak, and, worst of all for a macho Greek warrior, effeminate.
The not very subtle hint that Xenophon gives us here is that Persians are effectively controlled by their women, and for the ancient Greeks, that would've been a source of shame and dishonor.