Vahriz was a Deylamite spahbod (commander) in the service of the Sassanid Empire. He was the head of a small expeditionary force of low ranking Azatan (Azadan) nobility, numbering around 700, sent by Khosrau I to Yemen.
The Yemenites had requested Khosrau's assistance against the Ethiopians of Axum, who had occupied large parts of the country. Sayf ibn Dhi Yazan, the son of Dhu Yazan, went to Khosrau and offered him all of Yemen if his army would defeat the Ethiopians.[1]
Vahriz met Masruq, ruler of Yemen, in battle and killed Masruq with an arrow. Then the Ethiopians fled, Vahriz conquered Sana'a and then went on to conquer the rest of the country. Tabari reports that the main reason behind victory of Vahriz over the Axumites was the use of the panjigan (probably a ballista equipped with heavy darts), a piece of military technology with which the local peoples were utterly unfamiliar.
Vahriz then took up residence as the Persian governor of Yemen, which became a vassal state of the Sassanids until the arrival of Islam.