https://en.wikipedia.org/wiki/Parthian_Empire
It was the 3rd Iranian empire (I do not consider Elam to be Iranian) that fell to the Arabs, the Sassanian:
https://en.wikipedia.org/wiki/Sassanian_Empire
To an extent, as an Iranian, it is partially true that post Sassanian, no other Iranian dynasty had command over the entirety of historic Iranian lands and boundaries. The last Iranian dynasty, the Pahlavi dynasty of the 20th century came closest.
https://en.wikipedia.org/wiki/List_of_Iranian_dynasties_and_...
> There is an inferiority complex in Persian politics.
I'm quite confident that mindset is a thing of the past. (Look at China.) Currently of course we are burdened with a regime that is polluting Iranian culture. But this too shall pass, God willing.
[p.s. regarding other mis-statements]:
> Since Iran then was then subsequently ruled by Caliphs, Turkish Sultans and then western rulers.
https://en.wikipedia.org/wiki/Samanids
That's a pretty substantial piece of real estate, agreed?
> western rulers.
Possibly you are referring to the Pahlavi Shahs (?), in which case it important to point out that if the Shah of Iran was in fact a puppet of the West they would not have been so pleased to see him go. You may want to take a trip to Iran and ask the natives what are their feelings towards the Pahlavi dynasty these days ...