The principal dispute is about who should exercise authority over the Muslim community: the Sunni believe that a
leader or
caliph should be selected by the community, while the Shia hold that
caliphs can
only come from the descendents of the Mohammed's chosen successor, his cousin Ali.
They denied the validity of the succession of Sunni
Caliphs and Shi`a Imams, recognizing as Caliph
only the
leader elected from their own group.