The Abbasid Caliph who sat on the throne in Baghdad in 1100 was a man named al-Mustazhir bi'llah.

You have probably never heard of him.

This is not your fault. By 1100, the office of caliph had been almost entirely ceremonial for a century and a half. The actual government of the eastern Islamic world was being conducted by a rotating cast of regional sultans and viziers who used the caliph's name as a formal legitimation device but did not consult him on policy. The political history of the late Golden Age is, accordingly, the history of those sultans and viziers — Buyids, Seljuks, Khwarezmians, Ayyubids, Mamluks. The caliph remained in his palace. The empire moved on without him.

The shift began in 945, when a small Iranian dynasty called the Buyids (BOO-yids, sometimes spelled Buwayhids) took Baghdad.

The Buyids were Twelver Shia Muslims from the Caspian region of northern Iran. They were originally mountain warlords from the Daylam (a rugged region south of the Caspian Sea) who took service under Iranian and Iraqi rulers in the early tenth century, gradually accumulated military force, and by the 940s controlled most of Iran and parts of Iraq. In 945 the Buyid amir Mu'izz al-Dawla (moo-IZZ ad-DAW-lah, "Strengthener of the State" — the al-Dawla honorifics were a Buyid innovation that future regional rulers would emulate) entered Baghdad with his army, deposed the existing political establishment, and installed himself as the de facto ruler of the Caliphate's heartland.

The arrangement that followed was peculiar. Mu'izz al-Dawla and his Buyid successors did not abolish the Abbasid caliphate. They could have — they had the military force, and they had ideological grounds, since they were Shia and the Abbasid was a Sunni institution. Instead, they preserved the caliph as a formal ruler, took the title amir al-umara ("commander of commanders") for themselves, controlled the Caliphate's armies, taxes, and administration, and let the caliph maintain ceremonial functions and the religious symbolism of the office. The Buyid logic seems to have been pragmatic: the Sunni population they ruled would not accept a Shia caliph; abolishing the caliphate would create a religious-political vacuum they could not fill; far easier to rule through the existing institution while reducing it to a shell. The Buyids ruled the Caliphate's heartland for 110 years (945–1055) without ever attempting to replace the caliph.

The Buyid period was, intellectually, productive. The Buyid courts at Baghdad, Rey, Shiraz, and other cities patronized scholarship enthusiastically. Several of the Golden Age figures from earlier chapters worked under Buyid patronage — including Ibn Sina (Chapter 4), who served various Buyid courts before moving on, and al-Biruni (al-bee-ROO-nee, 973-1050), the great polymath geographer and astronomer who produced his Kitab al-Hind (a remarkably penetrating comparative study of Indian science and religion, written after he accompanied Mahmud of Ghazni on campaigns into India). Buyid Shi'ism was relatively non-aggressive; Sunni scholars were not persecuted, and most of the great Sunni religious institutions of Baghdad continued to operate normally. The Caliph al-Qadir issued the Qadiri Creed in 1018, a formal Sunni doctrinal statement responding to Buyid Shi'ism and Mu'tazilite rationalism, which the Buyid amirs allowed to circulate without suppression. The political shift to Shia rule did not reshape religious life on the ground.

What it did do was demonstrate that the Caliphate was no longer a unified state. After 945, the political authority that had once flowed from Baghdad outward had reversed direction. Local dynasties — Samanids in Khorasan, Ghaznavids in Afghanistan, Fatimids in Egypt, Buyids in Iraq and western Iran, smaller dynasties everywhere — were now running their own affairs, occasionally consulting Baghdad for legitimating gestures, but otherwise functioning as independent states. The Caliphate had become, in modern terms, a confederation of local rulers united by a shared religious institution rather than a unified empire.

The Buyids were displaced in 1055 by a new force: the Seljuk Turks.

The Seljuks were a confederation of Turkic-speaking peoples from the steppe north of the Aral Sea — descended ultimately from the Oghuz Turks who had moved into the Central Asian frontier of the Caliphate in the ninth and tenth centuries, converted to Sunni Islam, and gradually assimilated to the urban Islamic culture they encountered. The Turkic language family — distinct from both Iranian and Semitic, related at distance to Mongolian; the Turkic-speaking peoples are linguistically as different from Persians and Arabs as English-speakers are from Hindi-speakers, even though they had been Muslim for several generations and were culturally Persianate in important respects — had been gradually expanding into Iran and the Islamic east for some time. The Seljuk dynasty, founded by Tughril Beg (TOO-gril, ruled 1037-1063), was the first Turkic political force to seize central control of the Caliphate.

Tughril Beg's army entered Baghdad in 1055 at the invitation of the Sunni Caliph al-Qa'im, who had been chafing under Shia Buyid domination for over a century. The Buyids were expelled. Tughril Beg was given the title Sultan ("authority" or "ruler" — sultan had previously been a generic term but now became the formal title of the supreme political ruler holding power in the Caliphate's name) and married the caliph's daughter. The arrangement was the same as the Buyid arrangement in legal form: caliph as religious authority, sultan as political authority, separation of functions, shared sovereignty. The difference was that the Seljuks were Sunni. The Caliphate now had a Sunni political protector for the first time in over a century.

The Seljuks were also expansionist in a way the Buyids had not been. By 1071 they had taken control of most of the Iranian plateau, Iraq, and Syria, and were pushing into Anatolia.

The most consequential single battle of the late Golden Age was fought in 1071 in eastern Anatolia.

The Battle of Manzikert (MAN-zih-kert, fought near Lake Van in modern Turkey, August 26, 1071) pitted the Seljuk sultan Alp Arslan (ALP ar-SLAN, "Heroic Lion," ruled 1063-1072) against the Byzantine emperor Romanos IV Diogenes (ro-MAH-nos di-OG-ehn-eez). The Byzantines had been pursuing a policy of pushing eastward into Armenia and Mesopotamia for several decades; Romanos had assembled a large army (perhaps 40,000 men, including mercenaries) for what was supposed to be a decisive campaign against the Seljuks. The Seljuks responded with a smaller but more mobile force.

The battle was a disaster for the Byzantines. A combination of mercenary defections, tactical mistakes, and Seljuk skill at the steppe-style feigned retreat resulted in the destruction of the Byzantine field army and the capture of Romanos himself. He was the first Roman emperor to be taken prisoner in battle since Valerian had been captured by the Sasanian king Shapur I in 260 (Persian Empire Ch 8). Alp Arslan, displaying the chivalric gestures that medieval Islamic and steppe traditions both valued in conquerors, treated his captive honorably, signed a peace treaty, and released him. Romanos returned to Constantinople to find that his political faction had been overthrown in his absence; he was blinded, exiled, and died of his injuries the following year.

The strategic consequence of Manzikert was the opening of Anatolia to Turkic settlement. The Byzantine theme system (Byzantine Empire Ch 3 — the system of military-administrative provinces under regional generals that the empire had used to garrison and tax its Anatolian heartland since the seventh century) had been holding eastern Anatolia together for four centuries, and the destruction of the field army at Manzikert (covered in detail from the Byzantine side in Byzantine Empire Ch 7) was the moment that system broke. Turkic tribes streamed into the Anatolian highlands over the following decades, settling among the indigenous Greek-speaking population, gradually converting them or displacing them, and over the next four centuries transforming Anatolia from a Greek Christian province into the Turkish Muslim heartland that would eventually become the Ottoman Empire (Byzantine Empire Ch 7-11). What we now call Turkey is the result of Manzikert. Without the battle, modern Turkey would not exist as a Turkic-speaking nation.

The other strategic consequence was the call for help from Constantinople to Western Europe.

The Byzantine emperor Alexios I Komnenos (ko-NEE-nos, ruled 1081-1118), inheriting an empire shrunk by Manzikert and threatened on all sides, sent envoys to Pope Urban II in 1095 asking for Western military aid against the Seljuk advance. Alexios wanted what we would now call a mercenary force — Western European heavy cavalry to be incorporated into Byzantine command and used to retake lost provinces. What he got was something else.

In November 1095, Pope Urban II preached a sermon at the Council of Clermont in central France calling for a Western Christian military expedition to recover Jerusalem from Muslim rule. The sermon's exact text does not survive (we have several reconstructions written by chroniclers afterward, all subtly different from each other), but its basic structure is clear: Urban framed a campaign to assist the Eastern Christians as a meritorious religious act, offered participants the remission of sins, and connected the recovery of Jerusalem to the broader cause of Christian unity. The response was unexpected. Within months, tens of thousands of Western Europeans had taken the cross — the symbolic vow of pilgrimage with military intent — and were preparing to march east.

The First Crusade (1096-1099) was the first major military intervention by Western Europe in the Islamic world since the Carolingian campaigns three centuries earlier. It was, by any reasonable measure, an astonishing success — for the Crusaders. A peasant force called the People's Crusade was massacred in Anatolia early on, but the main armies of Frankish nobles successfully crossed Asia Minor (with reluctant Byzantine logistical support; relations between the Crusaders and Alexios soured almost immediately, neither side trusting the other), captured the city of Antioch in 1098 after a long siege and a famous battle in which the Crusaders, their food running out, sortied against a relief army and won an unexpected victory, and reached Jerusalem in June 1099. The siege of Jerusalem lasted six weeks. The city fell on July 15, 1099. The Crusaders sacked it.

The sack was unusually bloody even by the standards of medieval city captures. Contemporary Crusader sources — proudly — describe the killing of Muslim and Jewish inhabitants en masse, with chronicles citing knights riding through streets where the blood reached their horses' bridles. The numerical claims for casualties are inflated by both sides for their own reasons (Muslim sources to dramatize the atrocity, Crusader sources to celebrate it), but the consensus modern estimate is that several thousand to perhaps tens of thousands of inhabitants were killed in the days following the city's fall. The Muslim population of Jerusalem was effectively eliminated. The Jewish population was either killed or expelled. The Eastern Christian population was largely tolerated but had a difficult relationship with the Latin Crusaders.

The Crusaders established four Crusader states along the eastern Mediterranean coast: the Kingdom of Jerusalem, the County of Tripoli, the Principality of Antioch, and the County of Edessa. These were small Latin Christian polities embedded in a much larger Muslim world, surviving on European reinforcement, control of the coastal ports, and the chronic political division of the surrounding Islamic states. They were not ideologically central to the wider Islamic world's military-political agenda for most of the next ninety years — the Seljuk and Fatimid struggles for control of Syria absorbed most local attention — but they were a chronic irritant.

While the Crusader states were establishing themselves on the Levantine coast, the eastern part of the Islamic world was undergoing an institutional transformation that had begun a generation earlier and would shape its intellectual and religious life for centuries — and would, by the time of Saladin, supply the ideological infrastructure for the Sunni response to the Crusades.

Nizam al-Mulk (nih-ZAHM al-MULK, "Order of the Realm," c. 1018-1092) was the great vizier of the Seljuk sultans Alp Arslan and Malik-Shah I. He served as the de facto chief minister of the Seljuk empire for nearly thirty years, during which he reorganized the empire's administration along Sasanian-Persian lines (the same Persianizing tendency that had marked the early Abbasids — Chapter 1; the Iranian administrative tradition kept getting reused), wrote a famous mirror for princes — the Siyasatnama ("Book of Government," c. 1090) — that became a standard reference for Islamic political theory for centuries, and founded the institutional system that would define Sunni higher education for the rest of the medieval period.

The institution Nizam al-Mulk founded was the madrasa (mah-DRAH-sah, "place of study" — the Arabic noun derived from the verb "to study"). Madrasas as informal religious teaching institutions had existed for some time, but Nizam al-Mulk created the first network of state-funded, standardized, residential teaching colleges. The flagship was the Nizamiyya of Baghdad, founded in 1065, with branches established over the following years in Nishapur, Isfahan, Mosul, Basra, Marv, Herat, and other major cities. Each Nizamiyya was endowed with land or commercial revenues sufficient to support a faculty of professors, a residential community of students, a library, and a mosque. Students received free education, room, and board. The curriculum focused on Sunni law (especially the Shafi'i school, which Nizam al-Mulk personally favored) and Ash'ari theology, both taught according to standardized texts and methods.

The Nizamiyya network was the first state-funded higher education system in any civilization. It pre-dated the European universities (the University of Bologna, conventionally dated to 1088, was contemporary with the late Nizamiyya foundations; but the European universities developed organically from earlier cathedral schools rather than as a planned state initiative). It standardized Sunni religious education across the Caliphate. And it employed many of the great late-Golden-Age scholars — including al-Ghazali (Chapter 5), who taught at the Baghdad Nizamiyya before his nervous breakdown.

The Nizamiyya system also institutionalized the Ash'ari-Ghazalian theological synthesis as the standard Sunni orthodoxy. The professorial line at each madrasa enforced doctrinal continuity — a Nizamiyya graduate had a specific theological training that was the same in Baghdad as in Nishapur. Sunni Islam, by 1150, had acquired through the Nizamiyya system the doctrinal uniformity it had previously lacked. The fragmentation of legal schools (the four madhhabs) was preserved; what had become standardized was theology. By the time Saladin emerged a century later, the Sunni religious-political world he operated in had been shaped by the Nizamiyya — its judges, its preachers, its theologians had been trained on a common curriculum, and the call to confront the Crusader presence could be framed in the unified Ash'ari-Sunni terms the madrasa network had taught.

Nizam al-Mulk himself was assassinated in 1092 by a Nizari Ismaili Assassin (Mongol Empire Ch 5) sent by Hassan-i Sabbah, the founder of the Order of Assassins at the mountain fortress of Alamut. The Assassins were Nizari Ismaili Shia (Chapter 5) — a splinter of the Fatimid tradition that had organized into a militant order specializing in the targeted assassination of Sunni political and religious leaders. They had emerged in Iran in the late 1080s, established a string of mountain fortresses including the famous Alamut in the Alborz mountains north of modern Tehran, and conducted a 170-year campaign of high-value political assassination across the eastern Islamic world. Nizam al-Mulk was their first major victim. They would kill many more before being eliminated by the Mongols in 1256 (next chapter).

The Islamic political response to the Crusader presence took most of a century to organize, and when it came it was led by an unexpected figure.

Salah al-Din Yusuf ibn Ayyub (sah-LAH ah-DEEN, "Righteousness of the Faith," c. 1137-1193) — known to Western Europe as Saladin — was a Kurdish military commander whose family had served the Seljuks in northern Mesopotamia. The Kurds are an Iranian-speaking people of the highlands of eastern Turkey, northern Iraq, and western Iran; the Kurdish language is Indo-European, related to Persian, but distinct from it. The Kurds had been Sunni Muslims since the early Caliphate, but they retained a distinct ethnic identity and produced their own military aristocracy in the medieval period. Saladin's family rose under Seljuk patronage and then under the patronage of the Sunni Syrian ruler Nur al-Din (noor ah-DEEN), who had built a powerful Syrian state in the mid-twelfth century in opposition to both the Crusaders and the Shia Fatimids in Egypt.

Saladin was sent to Egypt by Nur al-Din in 1169 as part of an expedition to support a Fatimid faction in Cairo's internal politics. Through a combination of political skill and luck, he ended up as the Fatimid vizier — a Sunni Kurd running the central administration of a Shia caliphate. In 1171, on the death of the last Fatimid caliph, Saladin formally abolished the Fatimid Caliphate, restored Sunni control of Egypt, and proclaimed allegiance to the Abbasid caliph in Baghdad. The Friday prayer in Cairo's mosques, after 262 years of Fatimid Shia recitation, returned to the Sunni form. The change was massive — Egypt had been Shia for nearly three centuries and the institutional architecture of the country had been built around Shia legitimacy — but Saladin pulled it off without major popular resistance. The largely Sunni population of Egypt seems to have welcomed the shift; the Fatimid-loyalist faction in Cairo was small and isolated.

When Nur al-Din died in 1174, Saladin extended his control to Syria, marrying into Nur al-Din's family to claim political legitimacy. By 1186 he was the ruler of a unified Egyptian-Syrian state that surrounded the Crusader Kingdom of Jerusalem. He had also secured formal investiture from the Abbasid caliph as Sultan, giving him recognized Sunni political legitimacy across the Islamic east.

In 1187, Saladin invaded the Crusader states. The decisive engagement was the Battle of Hattin (HAH-teen, July 4, 1187), fought in the hills above the Sea of Galilee. The Crusader army, under the inept king Guy of Lusignan, was lured onto a waterless plateau, denied access to springs, surrounded by Saladin's forces, and destroyed over two days of fighting in summer heat. Most of the Crusader military aristocracy was killed or captured. Saladin reportedly executed the Knights Templar and Hospitaller prisoners (the two military religious orders, considered the most ideologically committed Crusaders) but spared most of the nobles for ransom. Within three months he had taken every major Crusader city in the Levant except Tyre. Jerusalem fell on October 2, 1187 — the Hijri date was the anniversary of the Prophet's Night Journey to the Temple Mount, a coincidence both sides noted.

Saladin's treatment of Jerusalem on its surrender was the moral inverse of the 1099 Crusader sack. The Christian inhabitants were not killed. They were allowed to leave on payment of ransom, with the poor (those who could not pay) released without payment after Saladin's brother contributed funds. Christian holy sites were preserved. Eastern Christian inhabitants — Greek and Armenian — were allowed to remain. The Muslim and Jewish populations who had been expelled or killed in 1099 were invited to return. The contrast between the two captures of Jerusalem was so striking that medieval European chroniclers — even crusader ones — sometimes acknowledged it. Saladin became, in European literary tradition, a kind of paragon of Islamic chivalry, eventually appearing in Dante's Inferno in Limbo (the section reserved for virtuous non-Christians) and serving as a sympathetic character in nineteenth-century Walter Scott novels.

The Christian response was the Third Crusade (1189-1192), led by Emperor Frederick Barbarossa of Germany (who drowned crossing a river in Anatolia before reaching the Holy Land), King Philip II Augustus of France (who returned home early), and most prominently King Richard I "the Lionheart" of England (1157-1199, the Plantagenet king of an Anglo-French realm covering much of modern France and England). Richard fought Saladin to a stalemate over three years of campaigning, recovered the coastal strip from Acre to Jaffa, but failed to recapture Jerusalem. The Treaty of Jaffa in 1192 ended the Crusade with Christians keeping the coastal Crusader states (substantially reduced from their 1187 peak) and Saladin keeping Jerusalem. The Crusader presence in the Levant would persist for another century, but it was now a coastal-strip residue rather than a major regional force.

Richard and Saladin never met in person, but a long-running medieval European tradition fictionalized chivalric exchanges between them. The most famous — Richard's horse killed in battle, Saladin sending him a replacement — is probably apocryphal but captures the genuine mutual regard the two commanders developed during the campaigns. Both were exceptional military leaders, and each recognized the other.

Saladin died in Damascus in 1193, six months after the Treaty of Jaffa. His family — the Ayyubid dynasty — divided his empire among its various branches and ruled Egypt and Syria as a fragmented confederation for the next sixty years, sometimes hostile to the Crusader states, sometimes in alliance with them, always in chronic internal conflict among Saladin's relatives.

A final note on the Khwarezmian Empire, because its story sets up Chapter 10.

The Seljuks themselves declined through the twelfth century, fragmenting into smaller successor sultanates as the dynasty's central authority weakened. By the late twelfth century, the dominant power in the eastern Islamic world was the Khwarezmian Empire — a successor state founded by the family of a Seljuk vassal who had originally governed the Khwarezm region (the same area along the lower Amu Darya from which al-Khwarizmi had hailed; the Iranian-speaking heartland of Central Asia). Under Ala ad-Din Muhammad II (1200-1220), the Khwarezmian state controlled most of Iran, Afghanistan, Transoxiana, and parts of the Iraqi border — an empire larger than the Seljuk empire had been at its peak.

The Khwarezmian sultan was, in 1218, the most powerful Muslim ruler in the eastern world. The Abbasid caliph in Baghdad was a religious figurehead. The Ayyubids in Egypt and Syria were dealing with the Crusader successor problems. The Seljuks of Anatolia (the Seljuks of Rum) were a regional power. The Khwarezmians outranked them all.

In 1218, a small caravan of Mongol merchants arrived at the Khwarezmian frontier town of Otrar carrying trade goods and a request for normal commercial relations. The Khwarezmian governor of Otrar — apparently acting on the sultan's orders, or at least with the sultan's tacit approval — accused the merchants of being spies, executed them, and seized their goods. Genghis Khan, the Mongol ruler whose envoys these had been, sent a second delegation requesting an explanation. The sultan had its members beheaded.

Genghis Khan now had what he later called the cause for the most destructive single military campaign in human history.

Islamic Golden Age

The Abbasid Revolution

The House of Wisdom

The Algebra and the Algorithm

Medicine, Optics, Engineering

The Schools and the Sufis

The Three Caliphates

Cordoba and the West

Trade and the Dirham Flood

The Seljuk Eclipse and the Crusades

The Mongol End