The Roma are a nomadic people who left Iran ages ago and their descendants live in Europe and Asia. Sadly they were a main target of the Nazis and many were killed.
Arabs are not the most common ethnic group in North Africa... it is widely accepted among historians that the Arabs conquered, spread Islam then left. Most didn't settle there, and those who did were not enough to outnumber the local indigenous Berber (Amazigh) population. To this day, culture, language, culinary traditions, music etc has remained distinctly Amazigh in most of North Africa... I think you should put a different clue.