13 events the sources record for this year, grouped by region.
What happened
China (1)
Hayashi no Azumahito and others returned from Bohai and reported that the king's letter did not conform to convention, so it was not accepted and they came back; the second ship, which carried the recorder (rokuji) Kamitsukeno no Tsugumasu, was separated and its whereabouts are unknown. (Nihon Kōki (Later Chronicles of Japan) 日本後紀 卷21)
Japan (7)
The Bohai envoy Ko Nan'yō returned home; a letter to the Bohai king praising good neighborliness was issued, and his ship was exchanged so that the vice-envoy could escort him. (Nihon Kōki (Later Chronicles of Japan) 日本後紀 卷21)
Fumiya no Watamaro was appointed general for the pacification of the barbarians, with Ōtomo no Imahito, Saeki no Mimaro and Sakanoue no Takakai as deputies. (Nihon Kōki (Later Chronicles of Japan) 日本後紀 卷21)
The Great Counselor Sakanoue no Tamuramaro died at his villa in Awada at the age of 54; the record notes that in Enryaku 23 he was raised to general for the pacification of the barbarians and achieved merit. (Nihon Kōki (Later Chronicles of Japan) 日本後紀 卷21)
Imperial edict to the general: entrust 1,000 captive soldiers to Kimiyakōbe no Oyashibe and others to attack Hei village; and deliberate and report on having 1,000 captive troops each from Mutsu and Dewa deployed in left and right formation between the eighth and ninth months. (Nihon Kōki (Later Chronicles of Japan) 日本後紀 卷21)
Report from Dazaifu: three Silla men, Kim Pahyeong (金巴兄), Kim Seungje (金乘弟) and Kim Sopa (金小巴), said that while transporting rice they met pirates and all their companions died; wishing to return home, they asked to be sent back on the same ship. Permission was granted. (Nihon Kōki (Later Chronicles of Japan) 日本後紀 卷21)
Imperial edict in response to the general's report: since the number captured and returned was not small, the Emishi should be moved to the inner provinces (chūgoku) and the captive prisoners settled in place. Newly captured Emishi should also be brought to the capital: the strong on foot, the weak given horses. (Nihon Kōki (Later Chronicles of Japan) 日本後紀 卷21)
General Fumiya no Watamaro reports: the official army has pacified the enemy completely in one stroke, so the garrison troops should be reduced; Shiwa Castle lies by a river and often suffers flood damage, so it should be moved. He also spoke of the 38 years of border conflict since the Hōki 5 era. (Nihon Kōki (Later Chronicles of Japan) 日本後紀 卷21)
West Asia (4)
To confirm the peace the emperor sends Haido, bishop of Basel, Hugo, count of Tours, and Ayo of Friuli to Constantinople (Royal Frankish Annals ARF a.811, Kurze 1895 p.133)
The governors of Mecca and Medina recognize al-Ma'mun as caliph (Al-Tabari, History of the Prophets and Kings Series III tom.2 (Arg.) [india.history.resource.86977], Annus 196)
Western Europe (1)
Twelve nobles of the Franks and of the Danes exchange oaths on the River Eider and confirm peace. From the Danish side come Hemming's brothers Hankin and Angantheo, and others (Royal Frankish Annals ARF a.811, Kurze 1895 p.134)