Byzantine Empire and Byzantium 137of SCIENCEin western Europe. As did his contemporary
John Buridan, Burley studied Aristotelian theories of
physics, especially on the origins and physiological
movements of animals. His commentaries on ARISTOTLE’s
treatises, especially his theories on movement, served as
an important basis for research and understanding. He
died in June 1344.
Further reading:Walter Burley, On the Purity of the
Art of Logic: The Shorter and the Longer Treatises,trans.
Paul Vincent Spade (New Haven, Conn.: Yale University
Press, 2000).
Buwayhids SeeBUYIDS.
Buyids(Buwayhids, Banu Bayah, Banu Buwaih) The
Buyids were a Turkish dynasty and were among the
most important of several dynasties established in
the ninth, 10th, and 11th centuries in the Middle East.
They were first established as mercenary foot soldiers
from the Caspian provinces of IRAN, especially the
mountainous province of Daylam. The Buyids them-
selves were the descendants of a common soldier, Bfiyih.
Such soldiers were called Daylamis or men from Daylam
and the Buyids were “the Daylami dynasty.” Largely
independent of the control of the caliphs of DAMASCUS
and BAGHDAD, the peoples of these mountainous areas
converted to Islam, in particular Shia Islam. This gave
them an ideological opposition to the ABBASIDcaliphs in
Baghdad. They first supported the Alids, but as they
attained real power, they became much less concerned
with such matters.
CREATION OF A STATEIn the early 10th century, the ABBASIDSwere no longer
able to field armies in western and central Persia. The
Buyids quickly figured out that they could control the
state. In 924 Imad al-Dawla (r. 934–949) overran the
southwestern Persian province of Fars and established his
own capital of Shiraz. From Fars he sponsored the con-
quest of central Persia by his younger brother, Rukn al-
Dawla, and in 945 he sponsored the conquest of Iraq by
his youngest brother, Muizz al-Dawla (r. 945–967).
Muizz al-Dawla established Buyid rule in IRAQby
taking Baghdad in December 945. This event made a Shi-
ite family the guardians of the Sunni Abbasid caliphate.
In 946 Muizz al-Dawla deposed the reigning caliph and
replaced him with another member of the family. It then
became clear that Buyid mayors of the palace or emirs
were going to employ the Abbasid caliphs as instruments
and fig leaves for their own power and policies.
Adud-al-Dawla (r. 978–983) pursued a successful
expansionist policy, but on his death and for most of the
next 70 years, members of the ruling dynasty engaged in
much internal conflict. From 1029 the increasing weak-
ness of the Buyid state encouraged outside intervention.
The SELJUKSestablished themselves in eastern Persia and
extinguished Buyid rule completely in the 1050s.BUYID RELIGIOUS AND CULTURAL LEGACIES
The constitutional and religious problems created by the
presence of the Shiites as effectively rulers over the Sunni
caliphate required a reconsideration of politics in Shiism
and Sunni. The Buyids found the Abbasid caliphs increas-
ingly valuable, particularly after 969, when in accord
with their activist version of Shiism, called Ismailism,
they tried to revive the universal caliphate and remove or
subordinate independent local dynasties and usurpers.
The Shiism of the Buyids was, however, doctrinally
vague, and they soon became adherents of the less
aggressive Twelver Shiism. With the varied cultural orien-
tation of the Buyids, as patrons of Arabic humanities and
the Persian royal tradition, and with tolerance required of
Shiite rulers of a population primarily Sunni, the period
of their domination in the 10th and 11th centuries made
it a period of great cultural accomplishment in literature,
science, and art, incorporating much of Iranian culture
into the center of Islam.
Further reading: Herbert Busse, “Iran under the
Buyids” in The Cambridge History of Iran,Vol. 4, The
Period from the Arab Invasion to the Saljuks,ed. R. N. Frye
(Cambridge: Cambridge University Press, 1975),
250–304; Mafizullah Kabir, The Buwayhid Dynasty of
Baghdad, 334/946–447/1055 (Calcutta: Iran Society,
1964); Claude Cahen, “Buwayhids,” Encyclopedia of
Islam, 1.1350–1357; Roy P. Mottahedeh, Loyalty and
Leadership in an Early Islamic Society,rev. ed. (London: I.
B. Tauris, 2001).Byzantine Church SeeCHURCH,EASTERNORTHODOX.Byzantine Empire and Byzantium The conversion
of Constantine and his foundation in 330 of the city
CONSTANTINOPLEon the site of the classical city of Byzan-
tium laid the basis for a future Byzantine Empire centered
on that city. In 395 the division between an Eastern and a
Western Roman Empire was made. It was still Roman but
became Christian during the fourth century.
The history of the Byzantine Empire has tradition-
ally been divided into three phases. The first era, from
the fifth to the seventh century, has been called an early
or proto-Byzantine Empire. The second was a medieval
state that lasted until 1204, when Constantinople was
sacked by western crusaders in the Fourth Crusade. The
last period ran from then until the fall of the city to the
OTTOMANTurks in 1453. It witnessed a constant shrink-
age of Byzantine-controlled territory. Throughout all of
these eras it had to struggle militarily with outside
invaders, sometimes advancing its frontiers, but far
more often suffering a slow retreat. Before its fall it had
spread its culture and religious doctrines and practices