[CdMGuy]

Excuse me, but Persia disappeared from the map a long, long time ago. These people are Iranians who like to be called Persians because it makes them feel more important. It is kind of like Italians being called Romans. Makes no sense at all unless the Italian lives in Rome.

[nickcarraway]

There are two answers. Persia was the exonym, but usage changed in 1935. But in today's usage, Iran is the country, but Persian is the ethnicity. Not all Iranians are Persian. About 60 to 65%.

Do you get mad that some people are called Jews, because you think they should all be called Israelis?