|Covid-19|King Charles the Younger, son of Charlemagne and ruler of Aquitaine, visits Monte Cassino and Capua, both in Beneventan territory. Prince Arechis II signs an agreement with the neighbouring Byzantine Duchy of Naples, called a 'pactum'.
Cyneheard, brother of the late king Sigeberht, ambushes and kills his rival Cynewulf of Wessex, while he is at Meretun (now called Marten) with his mistress. The Wessex nobles refuse to recognise Cyneheard as king.
Cyneheard is executed and succeeded by Beorhtric, through the support of King Offa of Mercia. His rival claimant to the Wessex throne, a distant nephew of the late king Ine, named Egbert, is driven across the Channel.
Egbert settles at the court of Charlemagne, and learns the arts of government during his time in Gaul. During his stay he meets Eadberht, a priest, who later becomes king of Kent.
June 11 – Battle of Fakhkh: A Hasanid Alid uprising in Mecca is crushed by the Abbasids. One of the Alids, Idris ibn Abdallah, flees to the Maghreb in western North Africa, where he later founds the Idrisid dynasty.
September 14 – Harun al-Rashid becomes the Abbasid caliph in Baghdad, upon the death of his brother Al-Hadi. He appoints Salim Yunisi as governor of Sindh and the Indus Valley.
Beatus of Liébana, monk and theologian, publishes his Commentary on the Apocalypse.
October 10 – Saga, emperor of Japan (d. 842)
Adelochus, archbishop of Strasbourg (d. 823)
Al-Ḥajjāj ibn Yūsuf ibn Maṭar, Muslim mathematician (d. 833)
Al-Ma'mun, Muslim caliph (d. 833)
Sahl ibn Bishr, Muslim astrologer (approximate date)
Tachibana no Kachiko, empress of Japan (d. 850)
September 14 – Al-Hadi, Muslim caliph (b. 764)
October 16 – Lullus, archbishop of Mainz
Abo of Tiflis, Christian martyr
Al-Rabi' ibn Yunus, Muslim minister (or 785)
Cyneheard the Ætheling, nobleman of Wessex
Cynewulf, king of Wessex
Desiderius, king of the Lombards (approximate date)
Diarmait mac Conaing, king of South Brega (Ireland)
Sakanoue no Karitamaro, Japanese general (b. 727)
Tipraiti mac Taidg, king of Connacht (Ireland)
Year 786 (DCCLXXXVI) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. The denomination 786 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.