Quraish refers to the Meccan tribe that Muhammad belonged to. It would become a prominant tribe in Mecca before the birth of Muhammad, being given guardianship over the Kaba. During the lifetime of Muhammad, the tribe split into different clans, and there were often rivalries among the clans. Muhammad's greatest opposition came from clans within his tribe that were threatened by his message. These rivalries would be central to the conflicts over the caliphate after Muhammad's death, and would lead to the Shia-Sunni divide in Islam.
