As far as I know, this source was first revealed by Jew scholar, Moshe Yegar’s research in his book, Muslims of Burma

The term Zerbadee (also spelled Zaedabardi, Zaerbad, or Zirbadi) originated from the Persian language and was used in ancient and colonial times to refer to Muslims in Myanmar (Burma) who were the descendants of intermarriages between foreign Muslim fathers (often Indian, Arab, or Persian traders) and local Burmese mothers. 

Origin and Meaning

• Persian Origin: The term is believed to be derived from Persian. Some sources suggest it comes from the Persian phrase Zir-bad (زیرباد), which possibly related to people living “downwind” or in a lower area relative to a geographic marker, or potentially the term meant “half-caste” or “mixed blood” in a historical context, though this specific etymology requires more specialist verification.
• Historical Usage: Historically, the term was a common designation in British colonial censuses and local society for the specific community of mixed Indian Muslim and Burmese descent. They were generally considered an Indian Muslim community rather than an indigenous Burmese ethnic group.
• Cultural Identity: Unlike the Rohingya, who are a distinct ethnic minority group concentrated in Rakhine State, the Zerbadees are generally linguistically and culturally integrated into the mainstream Bamar (Burmese) society, adopting Burmese language, customs, and lifestyles.