Fourth Fitna The Fourth Fitna or Great Abbasid Civil War was a conflict between the brothers al - Amin and al - Ma ' mun over the succession to the Abbasid Caliphate ' s throne . Their father , Harun al - Rashid , had named al - Amin as the first successor , but had also named al - Ma ' mun as the second with Khurasan granted to him as an appanage , while a third son , al - Qasim , had been designated as third successor . After Harun died in 809 , al - Amin succeeded in Baghdad . Encouraged by the Baghdad court , al - Amin began trying to subvert the autonomous status of Khurasan ; Qasim was quickly sidelined . In response , al - Ma ' mun ' s sought the support of the provincial elites of Khurasan , and made moves to assert his own autonomy . As the rift between the two brothers and their respective camps widened , al - Amin declared his own son Musa to be his heir , and assembled a large army . Al - Amin ' s troops marched towards Khurasan , but al - Ma ' mun ' s general Tahir ibn Husayn defeated them in the Battle of Rayy , and then invaded Iraq and besieged Baghdad itself . The city fell after a year , al - Amin was executed , and al - Ma ' mun became Caliph , but he remained in Khurasan and did not come to Baghdad . This allowed the power vacuum , which the civil war had created in the Caliphate ' s provinces , to grow , and several local rulers sprang up in Jazira , Syria and Egypt . In addition , the pro - Khurasani policies followed by al - Ma ' mun ' s powerful chief minister , al - Fadl ibn Sahl , and al - Ma ' mun ' s espousal of an Alid succession , alienated the traditional Baghdad elites , who saw themselves increasingly marginalized . Consequently , al - Ma ' mun ' s uncle Ibrahim was proclaimed rival Caliph at Baghdad in 817 , forcing al - Ma ' mun to intervene personally . Fadl ibn Sahl was assassinated and al - Ma ' mun left Khurasan for Baghdad , which he entered in 819 . The next years were taken up with consolidating al - Ma ' mun ' s authority and re - incorporating the western provinces , a process that was not completed until 827 . Some local rebellions , however , notably that of the Khurramites , dragged on for far longer . The conflict has been variously interpreted , in the words of the Iranologist Elton L . Daniel , as " a conflict over the succession between a rather incompetent , besotted al - Amin and his shrewdly competent brother al - Ma ' mun ; as the product of harem intrigues ; as an extension of the personal rivalry between the ministers al - Fadl b . Rabi ' and al - Fadl b . Sahl ; or as a struggle between Arabs and Persians for the control of the government " . Background . The origins of the civil war lie in the succession arrangements of Harun al - Rashid ( reign ed 786 – 809 ) , as well as the internal political dynamics of the Abbasid Caliphate . The two main contenders , Muhammad al - Amin and Abdallah al - Ma ' mun , were born six months apart in AH 170 ( 786 – 787 ) , with al - Ma ' mun being the elder . It was al - Amin however who was named first heir in 791 or 792 , while al - Ma ' mun followed in 797 , a sequence which was influenced by their lines of descent and their political implications : al - Amin had a solidly Abbasid lineage , being Harun ' s son by Zubayda , herself descended from the second Abbasid Caliph al - Mansur ( r . 754 – 775 ) , while al - Ma ' mun ' s mother was Marajil , a Persian concubine from Badhgis in Khurasan . While al - Ma ' mun ' s origin was less prestigious than the purely Arab al - Amin , his ties to Khurasan and the Iranian - dominated eastern provinces were an important factor in his choice as heir . In contrast to the exclusively Arab - ruled Umayyad Caliphate , the Abbasid state was under heavy Iranian , and particularly Khurasani , influence , since from the days of the Abbasid Revolution , which originated in Khurasan , the Abbasids relied heavily on Khurasanis as military leaders and administrators . Many of the original Khurasani Arab army ( " Khurasaniyya " ) that came west with the Abbasids were given estates in Iraq and the new Abbasid capital , Baghdad , and became an elite group known as the " abna ′ al - dawla " ( " sons of the state / dynasty " ) . Khurasan retained a privileged position among the Caliphate ' s provinces , and Harun al - Rashid in particular was careful to cultivate his ties with the Persian element of the Caliphate , not least through his promotion of the Khurasani Barmakid family to positions of power . Both al - Amin and al - Ma ' mun had been tutored in their youth by the Barmakids , al - Amin by al - Fadl ibn Yahya and al - Ma ' mun by Ja ' far ibn Yahya . While al - Amin would distance himself from the Barmakids and become closely associated with the " abna ′ " aristocracy of Baghdad , however , al - Ma ' mun remained influenced by Ja ' far and his associates . In 802 , Harun and the most powerful personalities of the Abbasid government made the pilgrimage to Mecca , where the definitive succession arrangement was drawn up : al - Amin would succeed Harun in Baghdad , but al - Ma ' mun would remain al - Amin ' s heir and would additionally rule over an enlarged and practically independent Khurasan . A third son , al - Qasim ( al - Mu ' tamin ) , was also added as third heir and received responsibility over the frontier areas with the Byzantine Empire ( the " al - thughur wa - l - ' awasim " ) . The stipulations of the agreement , extensively recorded by the historian al - Tabari , may however have been distorted by later apologists of al - Ma ' mun , especially as regards the extent of the autonomy granted to al - Ma ' mun ' s eastern viceroyalty . Almost immediately after it returned to Baghdad , in January 803 , the Abbasid court witnessed the abrupt fall of the Barmakid family from power . On the one hand , this decision may reflect the fact that the Barmakids may have become indeed too powerful for the Caliph ' s liking , but its timing suggests that it was tied to the succession issue as well : with al - Amin siding with the " abna ′ " and al - Ma ' mun with the Barmakids , and the two camps becoming more estranged every day , if al - Amin was to have a chance to succeed , the power of the Barmakids had to be broken . Indeed , the years after the fall of the Barmakids saw an increasing centralization of the administration and the concomitant rise of the influence of the " abna ′ " , many of whom were now dispatched to take up positions as provincial governors and bring these provinces under closer control from Baghdad . This led to unrest in the provinces , especially Khurasan , where , according to Elton L . Daniel , " Abbasid policies [ fluctuated ] between two extremes . One governor would attempt to extract as much wealth as he could from the province for the benefit of Iraq , the central government , and , not infrequently , himself . When the people protested loudly enough , such governors would be temporarily replaced by ones who would attend to local interests " . The Khurasani elites had a long - standing rivalry with the " abna ′ " . Although the latter now resided chiefly in Iraq , they insisted on retaining control of Khurasani affairs and demanded that the province ' s revenues be sent west to supply their salaries , something strongly resisted by the native Iranian elites . The resulting tension was eased when al - Fadl ibn Yahya , universally praised as a model governor , was appointed to Khurasan in 793 , but was re - fanned in 796 , when a member of the " abna ′ " , Ali ibn Isa ibn Mahan , was placed in charge of the province . His harsh taxation measures provoked increasing unrest , which expressed itself in Kharijite uprisings and , finally , a rebellion by the governor of Samarkand , Rafi ibn al - Layth . The latter uprising forced Harun himself , accompanied by al - Ma ' mun and the powerful chamberlain ( " hajib " ) and chief minister al - Fadl ibn al - Rabi , to travel to the province in 808 . Al - Ma ' mun was sent ahead with part of the army to Marv , while Harun stayed at Tus , where he died on 24 March 809 . Civil war between al - Amin and al - Ma ' mun , 809 – 813 . Upon Harun ' s death , al - Amin ascended the throne in Baghdad , where his popularity was great , while al - Ma ' mun remained at Marv , from where he planned to campaign against the remaining rebels . However , al - Amin recalled the army and treasury from the east , leaving al - Ma ' mun with little in the way of military forces . It was in this time that al - Ma ' mun came to rely upon his " wazir " , the former Barmakid protégé al - Fadl ibn Sahl , who began to implement a policy of conciliation and cooperation with the local elites , whose autonomy and privileges were guaranteed . The covenant of 802 however soon began to fall apart over Baghdad ' s centralizing ambitions and the dispute over the status of Khurasan : the " abna ′ " , led by Ali ibn Isa , whom Harun had imprisoned but who was now set free and appointed head of the Caliph ' s bodyguard , were joined by other influential officials , chief amongst them al - Fadl ibn al - Rabi , in demanding that Khurasan and its revenue return to the direct control of the central government , even if that meant breaking the stipulations of the Mecca agreement . The rift between the two camps manifested itself in 810 , when al - Amin added his own son , Musa , to the list of succession . Al - Amin ' s intention of overturning Harun ' s stipulations in favour of a direct patrilineal succession to his own sons was not unusual : all Abbasid caliphs from al - Mansur onwards had to struggle with their brothers or uncles to bequeath the throne to their sons , and Harun al - Rashid was even imprisoned during the brief reign of his elder brother al - Hadi ( r . 785 – 786 ) . It was only because al - Ma ' mun resided far from the Caliph ' s immediate area of control that he survived sharing this fate . Al - Amin then sent a delegation to Marv , asking al - Ma ' mun to return to Baghdad . After al - Ma ' mun , fearing for his safety , refused , al - Amin began to interfere with his brother ' s domain : he protested al - Ma ' mun ' s pardon to Ibn al - Layth after his surrender and asked for tribute from the governors of the western provinces of Khurasan as a sign of submission . He then demanded of his brother the cession of the western regions of Khurasan , the admission of caliphal tax and postal agents into the province , and the forwarding of the Khurasan ' s revenue to Baghdad . Al - Ma ' mun , who could not rely on large military forces and whose position was consequently weak , was at first inclined to accede to his brother ' s demands , but al - Fadl ibn Sahl dissuaded him from this course and encouraged him to seek support among the native population of Khurasan , who also opposed control by the caliphal court . Al - Ma ' mun , who was already favourably regarded after the excesses of Ali ibn Isa , consciously set about to cultivate the support of the local population , reducing taxes , dispensing justice in person , conceding privileges to the native princes , and demonstratively evoking episodes from the beginnings of the Abbasid movement in the province . He now became a " political magnet for Iranian sympathisers " ( El - Hibri ) , refused to cede his province or return to Baghdad , and began to gather around him those dissatisfied with Baghdad ' s centralizing policies or who had simply been left out of the share of spoils and power after the Abbasid Revolution . Under the influence of their respective chief ministers , al - Amin and al - Ma ' mun took steps that further polarized the political climate and made the breach irreparable . After al - Ma ' mun symbolically removed al - Amin ' s name from his coins and from the Friday prayer , in November 810 al - Amin removed al - Ma ' mun and al - Mu ' tamin from the succession and nominated his own sons Musa and Abdallah instead . al - Ma ' mun replied by declaring himself " imam " , a religious title which shied of directly challenging the Caliph but nevertheless implied independent authority , as well as hearkening back to the early days of the " Hashimiyya " movement which had carried the Abbasids to power . Despite the reservations of some of his senior ministers and governors , two months later , in January 811 , al - Amin formally began the civil war when he appointed Ali ibn Isa governor of Khurasan , placed him at the head of an unusually large army of 40 , 000 , drawn from the " abna ′ " , and sent him to depose al - Ma ' mun . When Ali ibn Isa set out for Khurasan , he reportedly took along a set of silver chains with which to bind al - Ma ' mun and carry him back to Baghdad . The news of Ali ' s approach threw Khurasan into panic , and even al - Ma ' mun considered fleeing . The only military force available to him was a small army of some 4 , 000 – 5 , 000 men , under Tahir ibn al - Husayn . Tahir was sent to confront Ali ' s advance , but it was widely regarded as almost a suicide mission , even by Tahir ' s own father . The two armies met at Rayy , on the western borders of Khurasan , and the ensuing battle ( 3 July 811 ) resulted in a crushing victory for the Khurasanis , in which Ali was killed and his army disintegrated on its flight west . Tahir ' s unexpected victory was decisive : al - Ma ' mun ' s position was secured , while his main opponents , the " abna ′ " , lost men , prestige and their most dynamic leader . Tahir now advanced westwards , defeated another " abna ′ " army of 20 , 000 under Abd al - Rahman ibn Jabala after a series of hard - fought engagements near Hamadan , and reached Hulwan by winter . Al - Amin now desperately tried to bolster his forces by alliances with Arab tribes , notably the Banu Shayban of Jazira and the Banu Qays of Syria . The veteran Abd al - Malik ibn Salih was sent to Syria to mobilize its troops along with Ali ibn Isa ' s son , Husayn . However , al - Amin ' s efforts failed due to the long - standing inter - tribal divisions between Qaysis and Kalbis , the Syrians ' reluctance to get involved in the civil war , as well as the unwillingness of the " abna ′ " to cooperate with the Arab tribes and to make political concessions to them . These failed efforts to secure Arab support backfired on al - Amin , as the " abna ′ " began to doubt whether their interests were best served by him . In March 812 , Husayn ibn Ali led a short - lived coup against al - Amin in Baghdad , proclaiming al - Ma ' mun as the rightful Caliph , until a counter - coup , led by other factions within the " abna ′ " , restored al - Amin to the throne . Fadl ibn al - Rabi , however , one of the main instigators of the war , concluded that al - Amin ' s case was lost and resigned from his court offices . At about the same time , al - Ma ' mun was officially proclaimed caliph , while Fadl ibn Sahl acquired the unique title of " Dhu ' l - Ri ' asatayn " ( " he of the two headships " ) , signifying his control over both civil and military administration . In spring 812 , Tahir , reinforced with more troops under Harthama ibn A ' yan , resumed his offensive . He invaded Khuzistan , where he defeated and killed the Muhallabid governor Muhammad ibn Yazid , whereupon the Muhallabids of Basra surrendered to him . Tahir also took Kufa and al - Mada ' in , advancing on Baghdad from the west while Harthama closed in from the east . At the same time , al - Amin ' s authority crumbled as supporters of al - Ma ' mun took control of Mosul , Egypt and the Hejaz , while most of Syria , Armenia and Azerbaijan fell under the control of the local Arab tribal leaders . As Tahir ' s army closed on Baghdad , the rift between al - Amin and the " abna ′ " was solidified when the desperate Caliph turned to the common people of the city for help and gave them arms . The " abna ′ " began deserting to Tahir in droves , and in August 812 , when Tahir ' s army appeared before the city , he established his quarters in the suburb of Harbiyya , traditionally an " abna ′ " stronghold . The Islamic scholar Hugh N . Kennedy characterized the subsequent siege of the city as " an episode almost without parallel in the history of early Islamic society " and " the nearest early Islamic history saw to an attempt at social revolution " , as Baghdad ' s urban proletariat defended their city for over a year in a vicious urban guerrilla war . Indeed it was this " revolutionary " situation in the city as much as famine and the besiegers ' professional expertise , that brought about its fall : in September 813 , Tahir convinced some of the richer citizens to cut the pontoon bridges over the Tigris that connected the city to the outside world , allowing al - Ma ' mun ' s men to occupy the city ' s eastern suburbs . Tahir then launched a final assault , in which al - Amin was captured and executed at Tahir ' s orders while trying to seek refuge with his old family friend Harthama . Sahlid dominance and reaction , 813 – 819 . The regicide of al - Amin soured al - Ma ' mun ' s victory . Tahir was soon transferred out of the public eye to an unimportant post in al - Raqqah , but his deed lastingly tarnished the prestige and image of the Abbasid dynasty . According to Elton Daniel , " It shattered the sacrosanct aura which had surrounded the person of the Abbasid caliphs ; For the first time , an Abbasid ruler had been humiliated and put to death by rebellious subjects " . As al - Ma ' mun remained in Marv and made no signs of returning to the caliphal capital , a wave of Arab antipathy towards al - Ma ' mun and his " Persian " supporters came to the fore in the western regions of the Caliphate , particularly in Baghdad and Iraq , which feared being degraded to a mere province . This was furthered when the new Caliph entrusted the governance of the state to Fadl ibn Sahl , who intended to permanently move the Muslim world ' s centre of power eastwards to Khurasan , where he and his circle could control the reins of power to the exclusion of other groups . Fadl was also responsible for side - lining many other supporters of al - Ma ' mun ; thus , when Harthama ibn A ' yan went to Marv to inform al - Ma ' mun of the real situation in the west , the Sahlids turned the Caliph against him and he was executed on charges of treason in June 816 . In response , Harthama ' s son Hatim led a short - lived revolt in Armenia . The result of these policies was that revolts and local power struggles erupted across the Caliphate , with only Khurasan and the frontier districts with the Byzantine Empire exempt from this turmoil . Iraq in particular descended into near - anarchy . The new governor of Iraq , Fadl ' s brother al - Hasan ibn Sahl , soon lost the support of the " abna ′ " . The local population ' s alienation from his regime was exploited by the Zaydi Alids , who on 26 January 815 rose in revolt at Kufa , led by former general Abu ' l - Saraya al - Sirri . The revolt spread quickly through Iraq as various groups with old grievances against the Abbasids used the opportunity to exact revenge . Thus at Basra , the revolt was led by the Alid Zayd , a son of the " imam " Musa al - Kadhim who had been executed in 799 on Harun al - Rashid ' s orders . The uprising came close to threatening Baghdad itself , and it was only through the intervention of the capable Harthama that it was quelled , with Abu ' l - Saraya being captured and executed in October . Secondary pro - Alid movements also seized control of Yemen ( under Ibrahim al - Jazzar , another son of Musa al - Kadhim ) and the Tihamah , including Mecca , where Muhammad al - Dibaj , a grandson of the Alid " imam " Ja ' far al - Sadiq , was proclaimed Caliph in November 815 . The suppression of these revolts was entrusted to Ali ibn Isa ' s son Hamdawayh , with an army of " abna ′ " . Hamdawayh was successful in subduing these provinces , but then attempted , unsuccessfully , to secede from the Caliphate himself . In 816 , to bolster his flagging prestige , al - Ma ' mun assumed the title " God ' s Caliph " . Taking note of the widespread Alid support in his western provinces , al - Ma ' mun not only spared the lives of the various Alid anti - caliphs , but on 24 March 817 also named the Alid Ali ibn Musa al - Rida , a third son of Musa al - Kadhim , as his heir apparent , and even changed the official dynastic colour from Abbasid black to Alid green . Although the seriousness of al - Ma ' mun ' s commitment to the Alid succession is uncertain — there are suggestions that Ali al - Rida was so old that he could hardly be expected to actually succeed al - Ma ' mun — its impact was disastrous : not only did it fail to produce any tangible popular support , but also provoked an uproar among the members of the Abbasid dynasty in Baghdad . Hasan ibn Sahl had already been forced to abandon the city , where various factional leaders now shared power , and the news of the Alid succession ruined his attempts at conciliation . Instead , on 17 July 817 the members of the Abbasid family in Baghdad nominated a new Caliph of their own , Harun al - Rashid ' s younger brother Ibrahim . Ibrahim received broad backing from the Baghdad elites , from Abbasid princes like al - Ma ' mun ' s younger brother Abu Ishaq ( the future Caliph al - Mu ' tasim , r . 833 – 842 ) , to old - established members of the bureaucracy like Fadl ibn al - Rabi ( who returned to his office as " hajib " ) , and leaders of the " abna ′ " . As the scholar M . Rekaya commented , " in other words , it was a revival of the war between the two camps [ Baghdad and Khurasan ] , dormant since 813 " . Ibrahim moved to secure control of Iraq , but although he captured Kufa , Hasan ibn Sahl , who had made Wasit his base of operations , managed to get to Basra first . However , the governor of Egypt , Abd al - Aziz al - Azdi , recognized Ibrahim as Caliph . In Khurasan , the Sahlids at first downplayed the events at Baghdad , falsely informing al - Ma ' mun that Ibrahim had merely been declared governor ( " amir " ) rather than Caliph . Finally , in December 817 Ali al - Rida succeeded in revealing to al - Ma ' mun the real situation in Iraq , and convinced him that that the turmoil in the Caliphate was far greater than the Sahlids presented it to be , and that a reconciliation with Baghdad was necessary . Al - Ma ' mun now resolved to assume personal control of his empire , and on 22 January 818 he left Marv and began a very slow journey west to Baghdad . Fadl ibn Sahl was murdered on 13 February , probably on al - Ma ' mun ' s orders , although the rest of his family was spared a persecution like that which had befallen the Barmakids . Indeed , Hasan in Sahl was for the time being confirmed in his brother ' s position , and al - Ma ' mun was betrothed to one of his daughters . Ali al - Rida also died during the march on 5 September , probably of poison . His burial place at Sanabad , now known as Mashhad , has become one of the major Shi ' a pilgrimage sites . In the meantime , back in Baghdad , Ibrahim faced desertions , rebellions and conspiracies , one of which involved his half - brother al - Mansur . Hasan ibn Sahl was able to use this turmoil and advance north , capturing Mada ' in . As the months passed , discontent in Baghdad grew . Ibrahim ' s supporters , including Fadl ibn al - Rabi , began abandoning him , and in April and July 819 there was a plot to take Ibrahim captive and surrender him to al - Ma ' mun ' s forces . Narrowly escaping from the latter conspiracy , Ibrahim abandoned the throne and went into hiding , opening the path for al - Ma ' mun to reclaim Baghdad . On 17 August 819 , al - Ma ' mun entered Baghdad without resistance , and all the political turmoil quickly subsided . Al - Ma ' mun now set about to reconcile himself with the opposition : he rescinded the Alid succession , restored black as the dynastic colour , sent Hasan ibn Sahl into retirement , and recalled Tahir from his exile in Raqqah . Al - Ma ' mun did however retain the title of " imam " , which became part of the standard caliphal titulature . During the 812 – 813 siege of Baghdad , Tahir had established close ties with the " abna ′ " , which now proved useful in smoothing their acceptance of al - Ma ' mun . Tahir was further rewarded with the governorship of Khurasan in September 821 , and when he died in October 822 , he was succeeded by his son , Talha . For the next fifty years , the Tahirid line would provide the governors of a vast eastern province centred on Khurasan , while also providing the governors of Baghdad , securing the city ' s loyalty to the caliphal government even after the capital was moved to Samarra . Reunification and pacification of the Caliphate , 820 – 827 . At the time al - Ma ' mun entered Baghdad , the western provinces of the Caliphate had slipped away from effective Abbasid control , with local rulers claiming various degrees of autonomy from the central government . Egypt had become divided between two bitterly hostile factions , one under Ubayd Allah ibn al - Sari which had come to control Fustat and the south , while his rival Ali ibn Abd al - Aziz al - Jarawi and his Qaysi Arabs controlled the north of the country around the Nile Delta . In addition , Alexandria was in the hands of a group of Andalusian exiles . In Syria , the traditionally dominant Qays tribe had taken control , led by Abdallah ibn Bayhas and Nasr ibn Shabath al - Uqayli . Ifriqiya had fallen under the control of the Aghlabids , while Yemen was troubled by pro - Alid revolts . Perhaps the most threatening rebellion of all was the anti - Muslim Khurramite movement , which controlled large parts of Azerbaijan and Armenia . To face these insurgencies , al - Ma ' mun turned to another of Tahir ' s sons , Abdallah ibn Tahir , to whom he entrusted the command of his army . Ibn Tahir first targeted Nasr ibn Shabath in northern Syria and the Jazira . Nasr was willing to acknowledge al - Ma ' mun ' s authority , but demanded concessions for his followers and remained hostile to the Abbasids ' Persian officials , so that he had to be browbeaten into submission by a show of force before his capital , Kaysum , in 824 – 825 . After securing his northern flank , Ibn Tahir marched through Syria into Egypt . There the two rivals , although not opposed in principle to al - Ma ' mun as Caliph , were eager to maintain the " status quo " , and had already repulsed an invasion in 824 under Khalid ibn Yazid ibn Mazyad . Ibn Tahir however managed to outmanoeuvre both , so that Ali al - Jarawi quickly went over to him , leaving Ubayd Allah to submit and face deportation to Baghdad . In Alexandria , Ibn Tahir secured the departure of the Andalusians , who left the city for the Byzantine island of Crete , which they conquered and transformed into a Muslim emirate . On his return to Baghdad in 827 , Abdallah ibn Tahir received a triumphal reception , and was appointed governor of Khurasan in 828 , replacing Talha . His place in the west was taken over by al - Ma ' mun ' s younger brother Abu Ishaq al - Mu ' tasim . In Yemen , another Alid revolt broke out in 822 under Abd al - Rahman ibn Ahmad , but al - Ma ' mun managed to secure his surrender by negotiations . Elsewhere , however , the process of consolidation was harder or failed completely : Aghlabid - controlled Ifriqiya was confirmed in its autonomous status , but effectively slipped entirely from Abbasid control , while in Azerbaijan , al - Ma ' mun ' s general Isa ibn Abi Khalid re - established control over the various local Muslim lords in the cities , but was unable to suppress the Khurramite revolt . Expeditions were sent against the Khurramites under Sadaka ibn Ali al - Azdi in 824 and Muhammad ibn Humayd al - Ta ' i in 827 – 829 , but both failed before the mountainous terrain and the Khurramites ' guerrilla tactics , with Ibn Humayd losing his life as well . It was not until the accession of al - Mu ' tasim , who employed his new military corps composed of Turkish slaves ( " mawali " or " ghilman " ) against the Khurramites , that their rebellion was suppressed , after years of hard campaigning , in 837 . Al - Ma ' mun ' s reign continued to be troubled by rebellions : a series of uprisings by the Zutt in lower Iraq , a three - year revolt against oppressive taxation in Egypt in 829 , where both the Christian Copts and the Muslims participated , as well as the unsuccessful revolt of Ali ibn Hisham , Ibn Humayd ' s successor as governor of Armenia and Azerbaijan . Aftermath and impact . The long civil war shattered the social and political order of the early Abbasid state , and a new system began to emerge under al - Ma ' mun , which would characterize the middle period of the Abbasid Caliphate . The most tangible change was in the elites who supported the new regime : the " abna ′ " , the old Arab families and the members of the Abbasid dynasty itself lost their positions in the administrative and military machinery , and with them their influence and power . The provinces of the Caliphate were now grouped into larger units , often controlled by a hereditary dynasty , like the Tahirids in Khurasan or the Samanids in Transoxiana , usually of Iranian descent . At the same time , however , al - Ma ' mun tried to lessen his dependence on the Iranian element of his empire , and counterbalanced them through the creation of two new military corps : Mu ' tasim ' s Turkish slaves , and the Arab tribal army of the Byzantine frontier , which was now grouped together and placed under the command of al - Ma ' mun ' s son al - Abbas . This system was further elaborated and acquired its definite characteristics in the reign of al - Mu ' tasim , who created a tightly controlled , centralized state , and expanded his Turkish corps into an effective military force with which he waged campaigns against the Byzantines and internal rebellions alike . Its leaders came to political power as provincial governors , while the old Arab elites were sidelined . With the doctrine of Mu ' tazilism , officially adopted in 829 after the end of the civil war , al - Ma ' mun also tried to reconcile doctrinal differences in Islam and reduce social inequities . At the same time , the willingness of al - Ma ' mun and his successors to embrace the non - Arab populations of the Caliphate , especially in the Iranian east , as well as to entrust the governance of these provinces to local dynasties with considerable autonomy , helped to end a long series of religious rebellions and reconciled these populations to Islam : the rate of conversion during al - Ma ' mun ' s reign increased markedly , and that was the time when most of the local princely families finally became Muslim . As El - Hibri comments , " in time this development represented a prelude to the emergence of autonomous provincial dynasties in the east , which would relate to the caliphal centre in nominal terms of loyalty only " . Sources .