12 events the sources record for this year, grouped by region.
What happened
China (3)
When the Weibo army raised Tian Xing, the court sent Pei Du to accept the abdication, and rewarded the three armies with gold. (Old Book of Tang (Jiu Tangshu), Annals 舊唐書 卷15 元和7年 10月)
Report from Tsushima: three Silla ships floated in the western sea, and one came ashore at Sasu harbor in Shimo-agata district. The crew were killed and four captured. Every night lights were seen toward Silla; notice was sent to Nagato, Iwami and Izumo to guard the strategic points (yōkai). (Nihon Kōki (Later Chronicles of Japan) 日本後紀 卷22)
The emperor visited the Shinsen garden, enjoyed the flowers, and had his literati compose poems: the beginning of the flower banquet (kaen). (Nihon Kōki (Later Chronicles of Japan) 日本後紀 卷22)
(Subject unclear: no name in the fragment) Besieges Adrianople and takes it by force; before that, withdraws with carts loaded with bronze lions, dragon statues and other items from the amphitheater. (Theophanes, Chronographia part_10.txt 줄 139~141)
Southern Europe (2)
Krum besieges and captures Develtos and moves its inhabitants to another land (during Michael's campaign). (Theophanes, Chronographia 줄 4205–4208)
Krum attacks Mesembria with siege engines and takes it within October. The capture of 36 siphons and Greek fire at the same place is recorded. (Theophanes, Chronographia 줄 4333–4344, 4449–4458)
Western Europe (3)
When Danish King Hemming dies, Sigifrid and Anulo struggle for the throne and both die in battle; the winning side of Anulo sets up his brothers Heriold and Reginfrid as kings. (The number of dead is in the damaged OCR text, 'XDCCCCXL'.) (Royal Frankish Annals ARF a.812, Kurze 1895 p.136)
Emperor Nikephoros dies fighting the Bulgars in Moesia, and his son-in-law Michael becomes emperor; in Constantinople he receives the envoys of Emperor Charles, sends them back, and confirms the peace (Royal Frankish Annals ARF a.812, Kurze 1895 p.136)
At the church in Aachen, Michael's envoys receive the treaty text, praising in Greek and calling the emperor basileus. On the way back, at St Peter's basilica in Rome, they receive the same treaty text from Pope Leo (Royal Frankish Annals ARF a.812, Kurze 1895 p.136)