The battle over southern Arabia, Aksumite–Persian wars. (Illustrated Summary)
During the 6th century, Arabia was either under the influence of the Roman Empire or the Sasanian Empire. But in the south of Arabia it was the Kingdom of Aksum that would attempt to assert itself into the region, leading to the Arab people of the south to call upon the Sasanians for help,
Sources:
-The Formation of Islam: Religion and Society in the Near East, 600-1800
by Jonathan P. Berkey
-The Throne of Adulis: Red Sea Wars on the Eve of Islam
By G.W. Bowersock
-History of Tabari - Volume 5 By Umair Mirza
-C. E. Bosworth, “ABNĀʾ,” Encyclopædia Iranica, I/3, p. 226-228