Nurse: Ah, she [Medea] has merited this city's good opinion, exile though she came (1)
Medea was accepted into Corinthian society when she first showed up. She was treated like any Greek woman. Now that her husband has dumped her, however, she's treated as a foreigner. The Greeks are very suspicious of her because she's a foreigner.
Nurse: her [Medea's] home she sacrificed to journey here with a man – oh – who disdains her now. (1)
Medea betrayed her father to help Jason capture the Golden Fleece. Doing so was a great sacrifice. She doomed herself to forever being a foreigner at a time in history when being foreign could be a very dangerous thing.
Nurse: Yes, now [Medea] knows at a terrible first hand what it is to miss one's native land. (1)
Though Medea has lived in Corinth for a while, she is still seen as an outsider. The fact that she has a Greek husband and has given him sons does little to stem the prejudice against her. Could this distrust on the part of the Greeks contribute to her rage?
Nurse: she glares with a bull-mad glaze (Or is it a lioness with her whelps) When anyone comes or speaks of helps. (29)
Greeks were of the opinion that all Asians, like Medea, were wild and emotional, especially the Persians, who they'd once defeated in war. Comments like this reflect this stereotype. It's almost like the Nurse is saying, "Well, you know how those people are."
Medea: I agree, of course, that a foreigner should conform, adapt to his society (31)
Medea recognizes her status as an outsider and concedes that she ought to act more Greek. Of course, her extreme grief and need for revenge doesn't seem particularly un-Greek to us. There's a ton of other tragedies that show Greeks behaving just as badly.
Medea: I am alone, […] uprooted from a foreign land. […] So, please, I ask you [Chorus] this: if I can find a way to pay my husband back – your silence. (31)
Here Medea uses her status as a foreigner to appeal to the Chorus. She plays on their sympathies, by emphasizing how isolated she is. It works pretty well, too. Medea manages to convince these Corinthian women to stand idly by while she assassinates their royal family.
Jason: So […] this is not the first time I have seen irrevocable damage done by a barbarous rage. (59)
When Jason uses the word "barbarous" he's making a direct reference to the fact that Medea is not Greek. The word comes from the Greek barbaros which simply means foreign. Now, of course, the word is associated with wild and unruly behavior. It's highly likely that the modern connotations come directly from Greek prejudice towards outsiders. With the line above, Jason seems to be blaming Medea's fury on the fact that she's a foreigner. (59)
Jason: you [Medea] have a home in Hellas [Greece] instead of some barbarian land. You have known justice (62)
Jason is under the impression that Medea should be grateful for the time she's spent in with him in Greece. He views himself as having rescued her from a dark and savage land. There would've most likely been some Athenians in the audience who agreed with Jason on this front. We wonder, however, if Euripides is trying to show his audience that they might be just a little bit full of themselves. After all, Medea is by far the most intelligent person in the play. She moves all the "enlightened" Greeks around her as easily as chess pieces. Would a stupid barbarian be able to do this?
Medea: Oh, the mistake I made was […] trusting the word of a man from Greece (137)
Medea is showing some prejudice of her own here. She seems to imply that all Greeks are just as untrustworthy as Jason. Medea, like all tragic heroines, is definitely not free from flaws.
Jason: At last I understand what I never understood before, when I took you from your foreign home to live in Greece, […] No woman in the whole of Hellas [Greece] would have dared so much (204)
Jason again reveals his Greek prejudice to outsiders with this statement. Of course, it's pretty understandable, since Medea has just slaughtered four people, including her own children. It's probably safe to say that the play didn't go a long way toward changing Athenians' opinions of foreigners.