The 810s decade ran from January 1, 810, to December 31, 819.
The 820s decade ran from January 1, 820, to December 31, 829.
The 830s decade ran from January 1, 830, to December 31, 839.
The 840s decade ran from January 1, 840, to December 31, 849.
The 860s decade ran from January 1, 860, to December 31, 869.
The 780s decade ran from January 1, 780, to December 31, 789.
Year 842 (DCCCXLII) was a common year starting on Sunday of the Julian calendar, the 842nd year of the Common Era (CE) and Anno Domini (AD) designations, the 842nd year of the 1st millennium, the 42nd year of the 9th century, and the 3rd year of the 840s decade.
Year 844 (DCCCXLIV) was a leap year starting on Tuesday of the Julian calendar.
Year 833 (DCCCXXXIII) was a common year starting on Wednesday of the Julian calendar.
Year 837 (DCCCXXXVII) was a common year starting on Monday of the Julian calendar.
Theophilos was the Byzantine Emperor from 829 until his death in 842. He was the second emperor of the Amorian dynasty and the last emperor to support iconoclasm. Theophilos personally led the armies in his long war against the Arabs, beginning in 831.
Abū Isḥāq Muḥammad ibn Hārūn al-Rashīd, better known by his regnal name al-Muʿtaṣim biʾllāh, was the eighth Abbasid caliph, ruling from 833 until his death in 842. A younger son of Caliph Harun al-Rashid, he rose to prominence through his formation of a private army composed predominantly of Turkic slave-soldiers. This proved useful to his half-brother, Caliph al-Ma'mun, who employed al-Mu'tasim and his Turkish guard to counterbalance other powerful interest groups in the state, as well as employing them in campaigns against rebels and the Byzantine Empire. When al-Ma'mun died unexpectedly on campaign in August 833, al-Mu'tasim was thus well placed to succeed him, overriding the claims of al-Ma'mun's son al-Abbas.
Bābak Khorramdin was one of the main Iranian revolutionary leaders of the Iranian Khorram-Dinān, which was a local freedom movement fighting the Abbasid Caliphate. Khorramdin appears to be a compound analogous to dorustdin "orthodoxy" and Behdin "Good Religion" (Zoroastrianism), and are considered an offshoot of neo-Mazdakism. Babak's Iranianizing rebellion, from its base in Azerbaijan in northwestern Iran, called for a return of the political glories of the Iranian past. The Khorramdin rebellion of Babak spread to the Western and Central parts of Iran and lasted more than twenty years before it was defeated when Babak was betrayed. Babak's uprising showed the continuing strength in Azerbaijan of ancestral Iranian local feelings.
Mazyar was an Iranian prince from the Qarinvand dynasty, who was the ruler (ispahbadh) of the mountainous region of Tabaristan from 825/6 to 839. For his resistance to the Abbasid Caliphate, Mazyar is considered one of the national heroes of Iran by twentieth-century Iranian nationalist historiography. His name means "protected by the yazata of the moon".
Ḥaydar ibn Kāwūs, better known by his hereditary title of al-Afshīn, was a senior general of Sogdian Iranian 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.
The sack of Amorium by the Abbasid Caliphate in mid-August 838 was one of the major events in the long history of the Arab–Byzantine Wars. The Abbasid campaign was led personally by the Caliph al-Mu'tasim, in retaliation to a virtually unopposed expedition launched by the Byzantine emperor Theophilos into the Caliphate's borderlands the previous year. Mu'tasim targeted Amorium, an Eastern Roman city in western Asia Minor, because it was the birthplace of the ruling Byzantine dynasty and, at the time, one of Byzantium's largest and most important cities. The caliph gathered an exceptionally large army, which he divided in two parts, which invaded from the northeast and the south. The northeastern army defeated the Byzantine forces under Theophilos at Anzen, allowing the Abbasids to penetrate deep into Byzantine Asia Minor and converge upon Ancyra, which they found abandoned. After sacking the city, they turned south to Amorium, where they arrived on 1 August. Faced with intrigues at Constantinople and the rebellion of the large Khurramite contingent of his army, Theophilos was unable to aid the city.
Al-Abbas ibn al-Ma'mun was an Abbasid prince and general, the son of the Abbasid caliph al-Ma'mun. A distinguished military leader in the Arab–Byzantine wars, he was passed over in the succession in favour of his uncle al-Mu'tasim. In 838, he was arrested for his involvement in a failed conspiracy against al-Mu'tasim, and died in prison.
Ujayf ibn Anbasa was one of the senior-most military leaders of the Abbasid Caliphate under the caliphs al-Ma'mun and al-Mu'tasim.
Ja'far ibn Dinar ibn Abdallah al-Khayyat was a ninth-century military commander for the Abbasid Caliphate.
