Year 771 (DCCLXXI) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. The denomination 771 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.
|Ab urbe condita||1524|
|Balinese saka calendar||692–693|
|Chinese calendar||庚戌年 (Metal Dog)|
3467 or 3407
— to —
辛亥年 (Metal Pig)
3468 or 3408
|- Vikram Samvat||827–828|
|- Shaka Samvat||692–693|
|- Kali Yuga||3871–3872|
|Japanese calendar||Hōki 2|
|Minguo calendar||1141 before ROC|
|Seleucid era||1082/1083 AG|
|Thai solar calendar||1313–1314|
897 or 516 or −256
— to —
898 or 517 or −255
- December 4 – King Carloman I, youngest son of Pepin III ("the Short"), dies (of a severe nosebleed, according to one source) at the Villa of Samoussy, leaving his brother Charlemagne sole ruler of the now reunified Frankish Kingdom. Gerberga, the widow of Carloman, flees with her two sons to the court of King Desiderius of the Lombards, at Pavia.
- Charlemagne repudiates his Lombard wife Desiderata, daughter of Desiderius, after one year of marriage. He marries the 13-year-old Swabian girl Hildegard, who will bear him nine children. Desiderius, furious at Charlemagne, plans a punitive campaign against the Franks and Rome.
- King Offa of Mercia defeats the Haestingas, and joins their little region to his sub-kingdom of Sussex.
- "Cathwulf, Kingship, and the Royal Abbey of Saint-Denis", by Joanna Story, Speculum
- Simon of Durham. Historia Regum. Ch. 47
- Simeon of Durham's. History of the Kings, p. 450