Sam2, I beg to differ. During the time of the gemara (200-700 CE by most accounts), the area was ruled by a number of groups, but mostly by Persians and Parthians, who shared ethnic and linguistic roots. Megilas Esther gives us, at an even earlier time, evidence of a distinct Persian ethnicity, not least in its use of Persian language, for example “Achashdarpanim” ” Pashos” which are clearly what we today call satraps and Pashas which are Persian terms, as well as “achashteranim”, and other words that had no equivalent in Lashon Hakodesh.
Until the rise of Islam in the mid 600’s, Arabs as a dominant ethnicity were confined to the Arabian peninsula and desert areas nearby, if they were nomadic beduin, as opposed to city dwellers. Given that we are told the Gemara was finished within 50-75 years of that time, and in the preceding 400 years the Jews lived in Persian dominated cities (for example, Pumpeditha, a Persian name) I think they knew who they lived among. Also, when the gemara wanted to, it identified the area (as opposed to the nation and the monarchy), as Bavel, a geographic term that hadn’t been applied to any ethnic group since the fall of the first beis hamikdash.
By the way, those North Africa Arabs? where do you think they came from? The second wave of Muslim conquest that swept them to the Atlantic. They originated in the Arabian peninsula too.
Lastly, and most importantly, The gemara in Yoma talks about the “end” coming when Edom will fight Paras.
[1]
Edom is interesting, because before it began being identified with Rome and the church, it was originally identified with nomadic detert and hill dwelling tribes of the descendants of Esav who lived generally south and east of Eretz Yisroel. In other words, Arabs.