|Covid-19|Battle of Akroinon: Following the disastrous Battle of Sebastopolis (see 692), Emperor Leo III has largely confined himself to a defensive strategy, while the Umayyad armies regularly launch raids into Byzantine-held Anatolia. Caliph Hisham ibn Abd al-Malik assembles a expeditionary force (90,000 men) under his son Sulayman ibn Hisham. One of these armies, 20,000 men strong under Abdallah al-Battal, is defeated at Akroinon (modern-day Afyon) by the Byzantines, led by Leo and his son, the future emperor Constantine V. About 6,800 Muslim Arabs, however, resist and manage to conduct an orderly retreat to Synnada (Phrygia).
October 26 – An earthquake strikes Constantinople and the surrounding countryside, causing destruction to the city's land walls and buildings.
The Berber tribes in the recently conquered region of Galicia (northwest Spain) rebel. This facilitates the establishment of an independent kingdom in the Cantabrian Mountains under King Alfonso I of Asturias.
Duke Thrasimund II recovers the duchy of Spoleto and kills Hilderic with Papal-Beneventian aid. He does not return the confiscated papal cities, and his alliance with Pope Gregory III ruptures.
December – King Liutprand of the Lombards attempts to counter the growing independence of the Lombard duchies in southern Italy.
King Eadberht of Northumbria marches his army north to attack the Picts. King Æthelbald of Mercia takes advantage of his absence, and ravages the city of York. Internal struggles re-emerge in Northumbria with the murder of Eardwine, probably the son of the late usurping king Eadwulf I.
King Æthelheard of Wessex dies after a 14-year reign. He is succeeded by his brother (and probably distant relative) Cuthred. Æthelbald of Mercia takes control of Berkshire from Wessex.
Battle of the Nobles: The Berber rebels under chieftain Khalid ibn Hamid al-Zanati defeat and overwhelm the Umayyad forces of Khalid ibn Abi Habib al-Fihri, near Tangier (Northern Morocco), undermining Arab domination in Islamic North Africa. The rebellion spreads in Al-Andalus (Spain), causing governor Ubayd Allah ibn al-Habhab to withdraw Moorish troops from many garrisons north of the Pyrenees.
Much to the delight of the citizens of Chang'an, the Chinese government of the Tang Dynasty orders fruit trees to be planted along every main avenue of the city, which enriches not only the diets of the people but also the surroundings (approximate date)
Fujiwara no Hirotsugu Rebellion: The Fujiwara clan led by Fujiwara no Hirotsugu, dissatisfied with the political powers in Japan, raise an army in Dazaifa (Kyushu) but is defeated by government forces.
The Khazars, a nation of the Black Sea steppe, though not ethnically Jewish, voluntarily convert to Judaism.
Cuthbert becomes archbishop of Canterbury after the death of Nothhelm (see 739).
Aurelius, king of Asturias (approximate date)
Gao Ying, chancellor of the Tang Dynasty (d. 811)
Layman Pang, Chinese Chán (Zen) Buddhist (d. 808)
Mashallah ibn Athari, Jewish-Arab astrologer (d. 815)
Waldo of Reichenau, Frankish abbot (approximate date)
Abdallah al-Battal, Arab general
Æthelburg, queen of Wessex
Æthelheard, king of Wessex
Æthelwold, bishop of Lindisfarne
Acca, bishop of Hexham (or 742)
Anna, wife of Artabasdos
Frithugyth, queen of Wessex
Gregory, duke of Benevento
Hilderic, duke of Spoleto
Khalid ibn Abi Habib al-Fihri, Arab general
Maysara al-Matghari, Berber rebel leader
Meng Haoran, Chinese poet
Rhain ap Cadwgan, king of Dyfed and Brycheiniog
Uqba ibn al-Hajjaj, Arab governor
Zayd ibn Ali, Arab imam and grandson of Husayn ibn Ali (b. 695)
Zhang Jiuling, chancellor of the Tang Dynasty (b. 673)
Year 740 (DCCXL) was a leap year starting on Friday (link will display the full calendar) of the Julian calendar. The denomination 740 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.