During the Sassanid period, the economic and political role of the Southern Arabs was limited. While the Muslim expansion would be conducted by Arabs from the northern interior, many Yemenis were also involved in this conquest. The emergence of Islam occurred during a phase of increased aridity in Hijāz and South Arabia, and following a decline in trade during the sixth century. The beginning of the eighth century, however, saw a period of renewed economic activity in the world-system.

A native of the merchant city of Mecca, the center of a pre-Islamic pagan cult, the Prophet Muhammad was the source of a new monotheism, Islam (meaning “submission [to God]”). Its holy book, the Koran, is for its believers the result of revelations received by Muhammad from 610 onward. The Makkans’ opposition to this new doctrine led the Prophet to leave the city and travel to Medina.