Siyah al-Uswari

Siyah, known in Arabic sources as Siyah al-Uswari ("Siyah the Aswar"; also spelled al-Aswari) was an Iranian nobleman, who served as the commander of a faction of the Sasanian asbaran unit, but later defected to the Rashidun Caliphate, where he continued serving as the commander of the asbaran (which became known as the Asawira).