The tribe to which Muhammad belonged. Sometime in the early sixth century, the Quraysh took control of the sanctuary in Mecca and by the turn of the seventh century had established themselves as prosperous merchants. Clan rivalries, however, caused a split within the tribe, a split which made itself felt during the lifetime of Muhammad and afterwards. Most significantly, the Abd Shams clan, which had initially rejected Muhammad's prophetic mission, gained pre-eminence through the Umayyad dynasty; their rivals, the Hashim clan to which Muhammad belonged, were represented by the Shi`ites and the Abbasids. According to Sunni political theory, the caliph must be from the Quraysh tribe.