Al-Mutawakkil in the context of "Mihna"

Ali ibn Muhammad al-Hadi (Arabic: عَلي إبن مُحَمَّد الهادي النَّقي‎; c. 7 March 828 – c. 21 June 868) was a descendant of the Islamic prophet Muhammad and the tenth Imam in Twelver Shia, succeeding his father, Muhammad al-Jawad (d. 835). Born in Medina in 828, Ali is known with the titles al-Hādī (Arabic: الهادي, lit. 'the guide') and al-Naqī (Arabic: النقي, lit. 'the distinguished'). After the death of his father in 835, most followers of al-Jawad readily accepted the imamate of Ali, who was still a child at the time. Drawing parallels with the story of young Jesus in the Quran, Twelver sources attribute an exceptional innate knowledge to Ali which qualified him for the imamate despite his young age.

As with most of his predecessors, Ali al-Hadi kept aloof from politics until he was summoned around 848 from Medina to the capital Samarra by the Abbasid caliph al-Mutawakkil (r. 847–861), known for his hostility towards Shias. There al-Hadi was held under close surveillance until his death in 868 during the caliphate of the Abbasid al-Mu'tazz (r. 866–869). Still, he managed to communicate with an underground network of representatives who organized the financial and religious affairs of the Shia community on his behalf. Most Shia sources hold the Abbasids responsible for his death at the age of about forty through poison, with the notable exception of al-Shaykh al-Mufid (d. 1022). His image in Twelver sources is that of a pacifist, persecuted Imam who endured numerous attempts by members of the Abbasid court to humiliate and dishonor him. These sources also allege more serious incidents of house search, temporary imprisonment, and even murder plots against al-Hadi.

The Anarchy at Samarra (Arabic: فوضى سامراء, romanized: fawḍā Sāmarrāʾ) was a period of extreme internal instability from 861 to 870 in the history of the Abbasid Caliphate, marked by the violent succession of four caliphs, who became puppets in the hands of powerful rival military groups.

The term derives from the then capital and seat of the caliphal court, Samarra. The "anarchy" began in 861, with the murder of Caliph al-Mutawakkil by his Turkish guards. His successor, al-Muntasir, ruled for six months before his death, possibly poisoned by the Turkish military chiefs. He was succeeded by al-Musta'in. Divisions within the Turkish army leadership enabled Musta'in to flee to Baghdad in 865 with the support of some Turkish chiefs (Bugha the Younger and Wasif) and the Police chief and governor of Baghdad Muhammad, but the rest of the Turkish army chose a new caliph in the person of al-Mu'tazz and besieged Baghdad, forcing the city's capitulation in 866. Musta'in was exiled and executed. Mu'tazz was able and energetic, and he tried to control the military chiefs and exclude the military from the civil administration. His policies were resisted, and in July 869 he too was deposed and killed. His successor, al-Muhtadi, also tried to reaffirm the Caliph's authority, but he too was killed in June 870. With Muhtadi's death and the ascension of al-Mu'tamid, the Turkish faction around Musa ibn Bugha, closely associated with Mu'tamid's brother and regent al-Muwaffaq, became dominant in the caliphal court, ending the "anarchy".

Abū ʿAbd Allāh Muḥammad ibn Jaʿfar ibn Muḥammad ibn Hārūn al-Muʿtazz bi-ʾLlāh (Arabic: أبو عبد الله محمد بن جعفر; 847 – 16 July 869), better known by his regnal title al-Muʿtazz bi-ʾLlāh (المعتز بالله, "He who is strengthened by God") was the Abbasid caliph from 866 to 869, during a period of extreme internal instability within the Abbasid Caliphate, known as the "Anarchy at Samarra".

Originally named as the second in line of three heirs of his father al-Mutawakkil, al-Mu'tazz was forced to renounce his rights after the accession of his brother al-Muntasir, and was thrown in prison as a dangerous rival during the reign of his cousin al-Musta'in. He was released and raised to the caliphate in January 866, during the civil war between al-Musta'in and the Turkish military of Samarra. Al-Mu'tazz was determined to reassert the authority of the caliph over the Turkish army but had only limited success. Aided by the vizier Ahmad ibn Isra'il, he managed to remove and kill the leading Turkish generals, Wasif al-Turki and Bugha al-Saghir, but the decline of the Tahirids in Baghdad deprived him of their role as a counterweight to the Turks. Faced with the assertive Turkish commander Salih ibn Wasif, and unable to find money to satisfy the demands of his troops, he was deposed and died of ill-treatment a few days later, on 16 July 869.

Abu Ja'far Muḥammad ibn Ja'far ibn Muḥammad ibn Hārūn al-Muntasir biʾLlāh (Arabic: أبو جعفر محمد; November 837 – 7 June 862), better known by his regnal title al-Muntasir biʾLlāh (المنتصر بالله, "He who triumphs in God") was the caliph of the Abbasid Caliphate from 861 to 862, during the "Anarchy at Samarra". The power struggle between al-Muntasir and his brother, al-Mu'tazz, backed by different factions, climaxed with the Turkic leaders plotting the murder of his father al-Mutawakkil. Following the assassination in 861, al-Muntasir assumed the caliphate with Turkic support.

His reign, only lasted six months, saw a shift in policies, including a more favorable stance towards the House of ʻAlī and the lifting of the ban on pilgrimage to the tombs of Hassan and Hussayn. Al-Muntasir engaged in military actions against the Byzantines, led by his general Wasif al-Turki, but his sudden death in June 862 resulted in a change of leadership, and al-Musta'in succeeded him as caliph. The military campaign continued briefly, with Wasif achieving success before returning to Samarra due to the change in government.

Abū al-ʿAbbās Aḥmad ibn Muḥammad ibn Muḥammad al-Mustaʿīn bi-ʾllāh (Arabic: أبو العباس أحمد بن محمد بن محمد; 836 – 17 October 866), better known by his regnal title al-Mustaʿīn (836 – 17 October 866) was the Abbasid caliph from 862 to 866, during the "Anarchy at Samarra". After the death of previous Caliph, al-Muntasir (who had not appointed any successors), the Turkic military leaders held a council to select his successor. They were not willing to have al-Mu'tazz or his brothers; so they elected Ahmad ibn Muhammad (أحمد بن محمد), a nephew of al-Mutawakkil, who took the regnal name al-Mustaʿīn bi-ʾllāh (المستعين بالله "he who looks for help to God").

Arab and other troops based in Baghdad, displeased at the choice, attacked the assembly, broke open the prison, and plundered the armory. They were attacked by the Turkic and Berber soldiers, and after some fighting in which many died, succumbed.

Bugha al-Sharabi ("Bugha the Cupbearer"), also known as Bugha al-Saghir ("Bugha the Younger") to distinguish him from his unrelated contemporary Bugha the Elder, was a senior Turkic military leader in the mid-9th century Abbasid Caliphate.

He served under Caliph al-Mutawakkil (r. 847–861) in Azerbaijan, but later led the conspiracy among the Turkic troops who killed the caliph. Closely allied to another Turkic officer, Wasif, Bugha held power at court under the caliphs al-Muntasir (r. 861–862) and al-Musta'in (r. 862–866), during the "Anarchy at Samarra". He fell into disgrace under al-Mu'tazz (r. 866–869), however, who resented both his influence and his role in the murder of al-Mutawakkil, his father. In 868, Bugha was imprisoned and executed at the Caliph's orders.

Wasif al-Turki (Arabic: وصيف التركي) (died October 29, 867) was a Turkic general in the service of the Abbasid Caliphate. He played a central role in the events that followed the assassination of al-Mutawakkil in 861, known as the Anarchy at Samarra. During this period he and his ally Bugha al-Sharabi were often in effective control of affairs in the capital, and were responsible for the downfall of several caliphs and rival officials. After Wasif was killed in 867, his position was inherited by his son Salih.

Abu’l-ʿAbbās Aḥmad ibn Jaʿfar ibn Muḥammad ibn Hārūn al-Muʿtamid ʿalā’Llāh (Arabic: أبو العباس أحمد بن جعفر; c. 842 – 14 October 892), better known by his regnal name al-Muʿtamid ʿalā 'llāh (المعتمد على الله, 'Dependent on God'), was the caliph of the Abbasid Caliphate from 870 to 892. His reign marks the end of the "Anarchy at Samarra" and the start of the Abbasid restoration, but he was largely a ruler in name only. Power was held by his brother al-Muwaffaq, who held the loyalty of the military. Al-Mu'tamid's authority was circumscribed further after a failed attempt to flee to the domains controlled by Ahmad ibn Tulun in late 882, and he was placed under house arrest by his brother. In 891, when al-Muwaffaq died, loyalists attempted to restore power to the Caliph, but were quickly overcome by al-Muwaffaq's son al-Mu'tadid, who assumed his father's powers. When al-Mu'tamid died in 892, al-Mu'tadid succeeded him as caliph.