Jayfar and Abd, princes of the powerful ruling Azd tribe which ruled Oman in collaboration with Persian governance, were sons of the client king Juland (frequently Al Julandā based on the Perso-Arabic pronunciation).[64] They embraced Islam peacefully on 630 AD upon receiving the letter sent from Muhammad through 'Amr ibn al-'As.[65] The Azd subsequently played a major role in the ensuant Islamic conquests. They were one of the five tribal contingents that settled in the newly founded garrison city of Basra at the head of the Persian Gulf; under their great general Al Muhallab ibn Abi Suffrah and also took part in the conquest of Khurasan and Transoxania.[66]