, Abu’l-ʿAbbās ʿAbd-Allāh, the seventh Abbasid caliph (r. 813-833), son of Hārun-al-Rašid (d. 809) by a Persian concubine.


MAʾMUN, Abu’l-ʿAbbās ʿAbd-Allāh (b. 786; d. near Tarsus in July-August 833), the seventh Abbasid caliph (r. 813-33; see ʿABBASID CALIPHATE), the son of Hārun-al-Rašid (d. 809) by a Persian concubine, named Marājel. He spent the earlier part of his reign in Khorasan, and only moved to Baghdad in 819.

Between 791 and 792, Hārun had named as his heir his son Moḥammad Abu Musā (r. as Amin 809-13), who was slightly younger than Maʾmun but had been born of a free mother, the Abbasid princess Zobayda (Ṭabari, III, pp. 610-12; Ebn al-Aṯir, ed. Beirut, VI, p. 122). During the pilgrimage (ḥajj) of 802, Hārun proclaimed in the Meccan Documents Maʾmun as second heir, and appointed him as governor of Khorasan. At that point, Hārun also named Qāsem al-Moʾtamen, another son, as third heir, and placed him in charge of the warfare along the Byzantine frontier (Yaʿqubi, II, pp. 501-510; Ṭabari, III, pp. 654-66; Azraqi, pp. 161-68; for more primary sources, see Ṭabari, tr., XXX, p. 184, ns. 673-74). The Khorasan appointment established Maʾmun’s connection with the province that had been key for the success of the Abbasid propaganda (daʿwa) in the 740s and 750s. After the pilgrimage of 802, the caliph turned against his vizier, and the Barmakids fell from grace. Subsequently, Maʾmun was tutored by Fażl b. Sahl (d. 818), a Zoroastrian convert to Islam.

Maʾmun and his guardian Fażl b. Sahl, as well as the vizier Fażl b. Rabiʿ (d. 822 or 24), were members of the caliph ’s entourage when in 808 Hārun marched his troops eastwards against Rāfeʿ b. Layṯ, the rebel in Transoxiana and Khorasan. During the campaign, in 809, the caliph died at Ṭus (Ṭabari, III, pp. 735-39; Ebn al-Aṯir, VI, pp. 207-8, 211-14). Amin returned immediately to Baghdad, where he had been proclaimed caliph. To buttress his central power in the capital, the new caliph recalled the army and the state treasury from Khorasan, thus depriving his brother of the means of properly exercising his gubernatorial responsibilities in the province (Ṭabari, III, pp. 765-71). Maʾmun and Fażl b. Sahl nonetheless reversed the oppressive fiscal and social policies of ʿAli b. ʿIsā b. Māhān (d. 812), who had been governor of Khorasan between 796 and 802 (Ṭabari, III, pp. 773-74; Daniel, pp. 177-78). They reduced land-tax (ḵarāj), and paid a special bonus to the province’s Arab and Iranian troops. They cultivated relationships with the landowners (dehqān), native Iranian princes (afšin), and even Turkish potentates on the fringes of Khorasan, such as the Yabḡu of the Oḡuz (see ḠOZZ) and the khan of the Qarluq. While the work of theologians (ʿolamāʾ) and jurists (foqahāʾ; see FEQH) was supported, Maʾmun personally presided over maẓālem sessions in the Great Mosque at Marv (Mary, Merv ) to hear complaints of the oppressed and the wronged. He thus acquired considerable popularity and built up valuable backing for his policies, calculating that the province’s military support would be highly advantageous in the forthcoming struggle with his brother.

Meanwhile, Amin set out deliberately to subvert his father’s succession arrangements. In 810, he disregarded the claims of Maʾmun and Muʾtamen, and proclaimed his sons Musā and ʿAbdallāh as first and second heirs to the throne (Jahšiāri, pp. 290-92; Ṭabari, III, 795-96; Ebn al-Atir, VI, p. 2499). Maʾmun wisely refused Amin’s order to return to Baghdad. Instead, he removed Amin’s name from the Friday prayer (ḵoṭba) and the coinage minted in Khorasan (sekka, see COINS AND COINAGE), and assumed for himself the title of “Imam of the Right Way” (Emām-al-Hodā). No previous Abbasid caliph had ever used this title, but it had resonances of divine approval and leadership of the Muslim community, harking back to the titulature of the first leaders of the Abbasid Revolution (al-dawla al-ʿAbbāsiya) in Khorasan (Ṭabari, III, 795-96). The stage was now set for a fierce civil war between the two brothers, which erupted in 811. A caliphal army under ʿAli b. ʿIsā b. Māhān was defeated by an army recruited from Arabs settled in Khorasan and from the Iranian military classes of Transoxiana, and Ḵʷārazm (see CHORASMIA); Amin’s general was killed at Ray by Ma’mun’s general, the Khorasanian Ṭāher b. Ḥos a yn (776-822). A second caliphal army under ʿAbd al-Raḥmān Jabala was likewise routed, and its commander killed. Further disasters drove Amin back to Baghdad, which was now besieged for thirteen months by Ṭāher and another of Ma’mun’s generals, Harṯama b. Aʿyan (d. 816). In 812, Maʾmun proclaimed himself caliph at Marv (Jahšiāri, pp. 305-6; Ṭabari, III, 841; Ebn al-Aṯir, VI, pp. 256-57), and appointed Fażl b. Sahl as his military and civil aide, duties reflected in his new title “Holder of the Two Commands” (Du ’l-Reyāsatayn). Baghdad fell, and Amin surrendered but was murdered on Ṭāher’s orders on the night of 24-25 September 813. Maʾmun does not seem to have been complicit in his brother’s death, though it was undoubtedly convenient for him. He now began a reign of some twenty years as both de facto and de jure head of the Abbasid Empire.

Maʾmun remained for six more years in what had been his provincial capital of Marv, entrusting lands to the west of Khorasan to various of his lieutenants in Iraq, such as Fażl’s brother Ḥasan b. Sahl. Despite his victory, times were difficult, and he faced many challenges to his power. The bases of the caliphate had been shaken because for the first time an Abbasid caliph was dethroned and killed. There was a loosening of respect for authority, and separatist tendencies showed themselves in revolts in the Jazira, Syria, Egypt, and the Caspian provinces so that Maʾmun’s authority at this moment hardly extended further west than Iraq. Only through the efforts of .ʿAbdallāh b. Ṭāher (d. 844) was the longstanding revolt in the Jazira ended during the course of 824 and 825, and Egypt brought back under caliphal control the following year. But in distant North Africa, the eastern Maghreb (Efriqiā) had to be left to the governors of the Aghlabid family. Above all, in Baghdad Maʾmun’s power was challenged by the old aristocracy of the Abnāʾ, who were the original supporters of the Abbasid Revolution, as well as by partisans of the ʿAlids and their claimants. The governor Ḥasan b. Sahl was forced to evacuate the capital. In 817, in an endeavor to acknowledge the ʿAlid claims, Maʾmun removed his brother Moʾtamen from the succession, and proclaimed ʿAli al-Reżā b. Musā Kāẓem, the Eighth Imam of the Shiʿa, as his heir. His decision caused an Abbasid legitimist reaction that led to the proclamation of Maʾmun’s uncle Ebrāhim b. Mahdi (r. 817-19) as rival caliph in Baghdad, over which he exercised precarious power for almost two years (Yaʿqubi, II, pp. 545, 547-48; Ṭabari, III, pp. 1002-1005, 1013-14, 1015-16, 1032-36; Ebn al-Aṯir, VI, pp. 341-42, 353-55). It was clearly vital that Maʾmun establish himself in the traditional capital of the Abbasid caliphate. In August 819, he made a triumphal entry into Baghdad after ten years of absence and could now be regarded as the ruler of a united caliphate. The new emphasis in his authority seems reflected in his changing relations with the Sahlids. Fażl b. Sahl was murdered at Saraḵs in 818, most probably at the caliph’s instigation, while Ḥasan b. Sahl gradually withdrew from public life, although he seems to have succeeded his brother as vizier and governor of Iraq (Yaʿqubi, II, p. 551; Ṭabari, III, pp. 1025-28, 1036-38; Ebn al-Aṯir, VI, pp. 346-48, 357-58). The year 819 accordingly marks the beginning of the second part of Maʾmun’s caliphate, in which he assumed a more personal and more assured rule.

Although Maʾmun’s personal abilities and the support of his very competent military commanders had enabled him to establish his rule over western Persia and Iraq, various internal revolts, sectarian uprisings, and the discontents of the ʿAlids continued nevertheless to plague these provinces from time to time. Northwestern Persia was racked by the neo-Mazdakite movement of the Ḵorramiya (see ḴORRAMIS IN BYZANTIUM) led by the heresiarch Bābak Ḵorrami, which began in Azerbaijan between 816 and 817, and soon affected the neighboring regions of Arrān and Jebāl. Maʾmun did not take the movement seriously until he moved to Baghdad in 819. Then he dispatched various generals against Bābak, but no one was successful in the mountainous terrain. The revolt was not to be suppressed until the reign of Maʾmun’s brother and successor Moʿtaṣem (r. 833-42), who sent his commander the Afšin Ḥaydar (Ḵeydār) b. Kāvus (see AFŠIN) to Azerbaijan. Because of these concerns Maʾmum could only in 830, towards the end of his reign, personally lead ḡazw (war against Byzantines resp. Christians), taking up the role prefigured by his adoption of the title emām. In 833, on campaign in Cilicia, Maʾmum fell ill and died (Yaʿqubi, II, pp. 573-74; Ṭabari, III, pp. 1134-41; Ebn al-Aṯir, VI, pp. 428-30).

After Maʾmun left Khorasan for Baghdad, the eastern lands were first entrusted, probably in 819 or 820, to Gassān b. ʿAbbād as vice-governor under Ḥasan b. Sahl. But in the next year, Ṭāher b. Ḥosayn managed, through intrigue, to secure this post, thus inaugurating the line of Taherid governors in Khorasan (Ṭabari, III, pp. 1042-43; Gardizi, ed. Ḥabibi, p. 134; Barthold, pp. 208-209). Ṭāher’s sudden death at Marv in 822 seems to have occurred just after he had shown signs of rebelliousness by dropping Maʾmun’s name from the ḵoṭba (Sourdel, 1958). Nevertheless, the caliph passed on the governorship of Khorasan to Ṭāher’s sons, Ṭalḥa (r. 822-28), and ʿAbdallāh (r. 828-45), successively. They appear to have ruled the province with moderation, and their local court, now transferred from Marv to Nishapur, was renowned as a center for Arabic culture and, possibly, for a nascent new Persian culture (see Bosworth, 1969a; 1969b). ʿAbd-Allāh b. Ṭāher, in particular, achieved the reputation of a wise and benevolent governor, with a concern for local rights and concerns.

On the remoter or more inaccessible fringes of Khorasan, where caliphal authority had been feeble or non-existent, Maʾmun’s policy was to work through his governors to control the local rulers, whose conversion to Islam, whenever appropriate, incorporated their lands within the Abode of Islam (Dār al-Eslām). These efforts, however, met with varying degrees of success. His generals could make no headway against the Kharijite leader Ḥamza b. Āḏarak (d. 828), whose revolt in Sistān had removed the rural areas of Sistān and Bost largely from central control, cutting off the flow of taxation to the caliphate from the province. Ḥamza’s partisans often raided into the Khorasanian countryside, on one occasion sacking Bayhaq. The rebellion only moderated, and did not end, when Ḥamza died a natural death in 828 (Bosworth, 1968, pp. 100-4).

Maʾmun’s policies had some short-term success in Transoxiana and the Caspian region (see CASPIAN SEA), though problems were left for the next caliph, Moʿtaṣem. The Afšins of the province of Ošrusana to the south of the middle Syr Darya river had nominally become vassals of the Abbasids in the later 8th century, but their allegiance to Baghdad was only intermittent. Soon after he had settled at Baghdad, Maʾmun was able to take advantage of a succession struggle in the principality among the Afšins. His expedition to Ošrusana included the Afšin Ḥaydar b. Kāvus who had fled to Maʾmum’s court in Baghdad (Ṭabari, III, pp. 1065-66; Ebn al-Aṯir, VI, p. 383; Barthold, pp. 210-11). Ḥaydar now became formally a Muslim, and soon afterwards succeeded to power in Ošrusana, thus bringing it into the Abbasid orbit.

The petty rulers and chiefs of the mountainous interior of the Caspian coastlands for long resisted caliphal control and the imposition of Islam. On various occasions in early Abbasid times, they had rebelled against the activities of caliphal tax collectors in their lands. Māzyār b. Qāren, a prince of the Qārenid family of Ṭabarestān, was involved in family disputes, and took refuge with Maʾmun at Marv between 816 an 817 (Yaʿqubi, II, p. 582; Ṭabari, III, p. 1298; Ebn al-Aṯir, VI, pp. 327-28). He became a Muslim at Maʾmun’s hands, and received the title of “Client of the Commander of the Faithful” (mawlā Amir al-moʾmenin). He later became co-governor of the mountain region, where he built up his military strength, and disregarded the Taherids, his overlords in Khorasan. When he attempted to extend his power into the settled lands of the Caspian plain, he aroused complaints of his tyranny from the Muslim population of the towns there (Ebn Esfandiyār, pp. 149-50). N evertheless, towards the end of his reign, Maʾmun made Māyzār sole governor of Ṭabarestān, and it was not until the reign of Maʾmun’s successor that Māzyār, after consolidating his power, rebelled against the central government and was definitively crushed.

Maʾmun ’s proclamation in 817 of the Imam ʿAli Reżā as his heir has already been mentioned. Among outwards signs of the change was the substitution of green for Abbasid black as the color for official robes, insignia, etc. The new color green was meant to highlight the role of the ʿAlids in the state (Jahšiāri, pp. 313; Yaʿqubi, II, pp. 545, 550; Ṭabari, III, pp. 1012-13, 1037-38; Ebn al-Aṯir, VI, pp. 326-27). The decision naturally caused consternation within the Abbasid family and among their traditional supporters, and was widely attributed to the maleficent influence of the pro-Persian vizier Fażl b. Sahl (see ʿALI AL-REŻĀ). It seems, however, that the decision was purely that of Maʾmun , who wished to buttress his military and political power as caliph by a religious and moral authority. The grand reconciliation of the hitherto rival branches of the Hashemite family, the ʿAlids and the Abbasids, was to be given physical embodiment by marriage alliances between the respective offspring of the caliph and the Imam (Gabrieli; Sourdel, 1962). Any such hopes were, in any case, ended by ʿAli Reżā’s sudden death at Ṭus in 818, after which Maʾmun reverted to the Abbasid color of black for ceremonial usages (Yaʿqubi, II, p. 551; Ṭabari, III, pp. 1037-1038; Masʿudi, pars. 2746, 2748, tr. IV, pp. 1121-22).

Maʾmun had a questing mind, engaged in various spheres of learning. In his academy in Baghdad, the House of Wisdom (Bayt al-Ḥekma), he encouraged the translation activities of scholars. He tried to move the authority of his office on a new level, so that the caliph as temporal head of the Islamic community could also assume the theological authority to define such basic questions of the faith as the createdness of the Qurʾān. In the last months of his life Maʾmun set in motion the wheels of a process of inquisition, the so-called meḥna (Ar. lit. testing, trial), which was to enforce his pro-Moʿtazelite views, but these efforts were cut short by his death. The meḥna was enforced, both during Maʾmun ’s last days and in the ensuing reign of Moʿtaṣem, in the Arab lands of the Fertile Crescent, from Egypt to Iraq, and the Hejaz. The situation in the Persian lands under Taherid control is unclear, and there is no definite evidence that the meḥna ever affected Khorasan and the eastern provinces to any notable degree (Hinds, p. 3; cf. Nawas, pp. 30-33).



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July 20, 2009

(C. Edmund Bosworth)

Originally Published: July 20, 2009

Last Updated: July 20, 2009