Al-Mu'tasim in the context of "Al-Muhtadi"

Samarra (Arabic: سَامَرَّاء, Sāmarrāʾ) is a city in Iraq. It stands on the east bank of the Tigris in the Saladin Governorate, 125 kilometers (78 mi) north of Baghdad. The modern city of Samarra was founded in 836 by the Abbasid caliph al-Mu'tasim as a new administrative capital and military base. In 2003 the city had an estimated population of 348,700. During the Iraqi Civil War (2006–08), Samarra was in the "Sunni Triangle" of resistance.

The archeological site of Samarra still retains much of the historic city's original plan, architecture and artistic relics. In 2007, UNESCO designated it a World Heritage Site.

The 9th century was a period from 801 (represented by the Roman numerals DCCCI) through 900 (CM) in accordance with the Julian calendar.

The Carolingian Renaissance and the Viking raids occurred within this period. In the Middle East, the House of Wisdom was founded in Abbasid Baghdad, attracting many scholars to the city. The field of algebra was founded by the Muslim polymath al-Khwarizmi. The most famous Islamic scholar Ahmad ibn Hanbal was tortured and imprisoned by Abbasid official Ahmad ibn Abi Du'ad during the reign of Abbasid caliph al-Mu'tasim and caliph al-Wathiq. In Southeast Asia, the Mataram kingdom reached its zenith, while Burma would see the establishment of the major kingdom of Pagan. Tang China started the century with the effective rule of Emperor Xianzong and ended it with the Huang Chao Rebellion. In America, the Maya experienced widespread political collapse in the central Maya region, resulting in internecine warfare, the abandonment of cities, and a northward shift of population.

The dirham, dirhem or drahm is a unit of currency and of mass. It is the name of the currencies of Morocco, the United Arab Emirates and Armenia, and is the name of a currency subdivision in Jordan, Libya, Qatar and Tajikistan. It was historically a silver coin.

Ḥaydar ibn Kāwūs (Arabic: حيدر بن كاوس, Persian: خِیذَر اِبنِ کاووس, romanized: Kheyzar ebn-e Kāvus), better known by his hereditary title of al-Afshīn (Arabic: الأفشين, Persian: اَفشین, romanized: Afshin), was a senior general of Sogdian descent at the court of the Abbasid caliphs and a vassal prince of Oshrusana. He played a leading role in the campaigns of Caliph al-Mu'tasim, and was responsible for the suppression of the rebellion of Babak Khorramdin and for his battlefield victory over the Byzantine emperor Theophilos during the Amorium campaign. Eventually he was suspected of disloyalty and was arrested, tried and then executed in June 841.

Samarra is a city in central Iraq, which served as the capital of the Abbasid Caliphate from 836 to 892. Founded by the caliph al-Mu'tasim, Samarra was briefly a major metropolis that stretched dozens of kilometers along the east bank of the Tigris, but was largely abandoned in the latter half of the 9th century, especially following the return of the caliphs to Baghdad.

Due to the relatively short period of occupation, extensive ruins of Abbasid Samarra have survived into modern times. The layout of the city can still be seen via aerial photography, revealing a vast network of planned streets, houses, palaces and mosques. Studies comparing the archeological evidence with information provided by Muslim historians have resulted in the identification of many of the toponyms within the former city.

The Mihna (Arabic: محنة خلق القرآن, romanized: miḥna khalq al-qurʾān, lit. 'ordeal of Quranic createdness') was a period of religious persecution instituted by the Abbasid caliph al-Ma'mun in 833 in which Sunni scholars were punished, imprisoned, or even killed unless they conformed to Mu'tazilite doctrine. The policy lasted for eighteen years (833–851) as it continued through the reigns of al-Ma'mun's immediate successors, al-Mu'tasim and al-Wathiq, and four years of al-Mutawakkil who reversed it in 851.

The abolition of Mihna is significant both as the end of the Abbasid Caliph's pretension to decide matters of religious orthodoxy, and as one of the few instances of religious persecution among fellow Muslims in Medieval Islam.

Ja'far ibn Muḥammad ibn Hārūn al-Mutawakkil ʿalā Allāh (Arabic: جعفر بن محمد بن هارون, romanized: Jaʿfar ibn Muḥammad ibn Hārūn); March 822 – 11 December 861, commonly known by his regnal name al-Mutawwakil ala Allah (Arabic: المتوكل على الله, romanized: al-Mutawakkil ʿalā Allāh, lit. 'He who relies on God'), was the tenth Abbasid caliph, ruling from 847 until his assassination in 861. He succeeded his brother, al-Wathiq (r. 842–847), and is known for expanding the empire to its maximum extent. He was deeply religious, and is remembered for discarding the Muʿtazila, ending the Mihna (a period of persecution of Islamic scholars), and releasing Ahmad ibn Hanbal. He is also known for his tough rule, especially with respect to non-Muslim subjects.

He was assassinated on 11 December 861 by the Turkic guard with the support of his son, al-Muntasir, marking the beginning of the period of civil strife known as the "Anarchy at Samarra".

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.

Ahmad ibn 'Abdallah al-Marwazi, known as Habash al-Hasib (Persian: حبش الحاسب, lit. 'Abyssinian calculator', died c. 869) was a Persian astronomer, geographer, and mathematician from Merv in Khorasan, who discovered the trigonometric ratios tangent, and cotangent. Al-Biruni who cited Habash in his work, expanded his astronomical tables.

Habash al-Hasib flourished in Baghdad, and died a centenarian some time between 864 and 874 possibly in Abbasid Samarra. The title "Habash" (Abbyssian) may refer to dark skin color. He worked under two Abbasid caliphs, al-Ma'mun and al-Mu'tasim.