death, and Abu Bakr (r. 632–634) became the first
caliph (successor to the Prophet) of the Muslim
community. This consensual understanding of
legitimate aUthority eventually became identified
with the Umayyad and Abbasid Caliphates, and
the Sunni branch of Islam.
In 656 Ali finally became the caliph after the
assassination of Uthman ibn aFFan (r. 644–656),
the third caliph, and he established his capital
in the city of Kufa in iraq. Ali’s legitimacy, how-
ever, was contested by his Meccan rivals. He
successfully defeated three of his major oppo-
nents—aisha (Muhammad’s widow) and Talha
and al-Zubayr (respected companions oF the
prophet)—at the Battle of the Camel in southern
Iraq. He was then forced to confront Muawiya ibn
Abi Sufyan (d. 680), the leader of the Umayyad
clan of the qUraysh. Ali and Muawiya fought until
the conflict was settled by arbitration at Siffin,
which left some of Ali’s supporters, known as the
khaWariJ (separatists), discontented. One of them
assassinated Ali in Kufa in 661. Ali’s son Hasan
agreed to recognize Muawiya as the next caliph,
and Muwawiya founded the Umayyad caliphate
with Damascus as its capital in 661. Consequently,
Ali’s second son, Husayn, launched a campaign
to win back the caliphate, but he was killed in
680, together with many of his supporters, by an
Umayyad army at karbala while traveling to join
his supporters in Kufa.
The historical split between Sunnis and Shiis
can therefore be traced to what was originally a
political dispute over succession to leadership in
the Muslim community. However, much of what
scholars know about this period of Islamic history
is based on accounts told from Sunni points of
view that prevailed several centuries later. Scholars,
therefore, have an incomplete understanding of
Shiism’s development in the early period. During
the ninth century the Shia began to maintain that
Ali and his heirs, known as the Imams, had suf-
fered martyrdom at the hands of unjust and corrupt
Sunni Muslim rulers. The unfortunate outcome
of Shii political expectations and Shii belief in the
just cause of their Imams eventually evolved into
the distinctive Shii belief in sanctification through
the deaths of the infallible Imams and belief in a
messianic redeemer, known as the imam mahdi,
who would come in the endtimes. The shift in the
worldview of the Shii movement occurred gradu-
ally between the seventh and 10th centuries, and
it was probably influenced by Jewish and Christian
beliefs in martyrdom and messianic redemption
circulating in the Middle East at the time.
The fate of the Imams, coupled with a history
of periodic persecution, led many Shii groups to
develop a doctrine that allowed for pious conceal-
ment, known as taqiyya, of their true Shii identity
for self-protection. ashUra, the commemoration of
the death of Husayn at Karbala during Muharram,
the first month in the Islamic lunar year, began to be
observed as the most important Shii holiday during
the 10th century, under the protection of the Shii
Buyid dynasty that ruled in the name of the Abbasid
caliph. In addition to belief in the return of a hidden
imam in the endtimes, most of the Shia also main-
tained that the Imams would intercede for the righ-
teous on JUdgment day. Another identifying trait of
Shiism that developed in this period was devotion
to Muhammad and his descendants through Ali and
Fatima, known as the People of the House (ahl al-
bayt). Sunnism also has held the prophet Muham-
mad’s family in high regard, but its understanding of
Islam has given greater importance to the sharia. In
the Sunni understanding of the sharia, it is Muham-
mad and his Companions who have precedence,
rather than his family per se.
An estimated 12 to 15 percent of the world’s
Muslim population today belongs to the Shii
branch of Islam, equal to between 156 and 195
million adherents (out of a total of around 1.3
billion Muslims). Almost all Shiis belong to one
of three major sects, basically distinguished from
each other according to which Imams they recog-
nize and which they do not. Each tradition has
also developed its own specific doctrines, rites,
and concepts of authority (for details, see entries
for each tradition). The largest tradition is known
as tWelve-imam shiism, and its followers are called
the Twelvers, the Ithnaashariyya, and the Imamis.
They recognize Musa al-Kazim (d. 799), the son
of JaaFar al-sadiq (d. 765) as the seventh Imam,K 624 Shiism