Al-Wathiq in the context of "Al-Mutawakkil"

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 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.

Abū Isḥāq Muḥammad ibn Hārūn ibn Muḥammad ibn Hārūn al-Muhtadī bi-ʾLlāh (Arabic: أبو إسحاق محمد بن هارون الواثق‎; c. 833 – 21 June 870), better known by his regnal name al-Muhtadī bi-ʾLlāh (Arabic: المهتدي بالله, "Guided by God"), was the Caliph of the Abbasid Caliphate from July 869 to June 870, during the "Anarchy at Samarra".