They were converted to Islam at the hand of Abu Dharr al-Ghifari, one of prophet's Muhammad companions who was exiled to Sham (modern day Syria and Lebanon) in the early 7th century AD.
They were converted at the hand of Abu Dharr al-Ghafari. He was exiled by Uthman to Sham (modern day Syria and Lebanon), so that he would be under the eyes of Muawiya in the early 7th century AD.