11 events the sources record for this year, grouped by region.
What happened
China (3)
Report from Mutsu: more than two hundred teki (barbarians) from Watarishima arrived at Kesen district. As they were outside the jurisdiction, officials tried to send them back, but they asked to stay until spring, saying it was hard to cross the sea in winter. Permission was granted and clothing and provisions (igyō) were given. (Nihon Kōki (Later Chronicles of Japan) 日本後紀 卷20)
By order of the retired emperor, an attempt was made to move the capital back to Heijō; Tamuramaro, Fujiwara no Fuyutsugu and Ki no Tanoe were made palace construction commissioners (zōgūshi). This began the Kusuko Incident. (Nihon Kōki (Later Chronicles of Japan) 日本後紀 卷20)
The retired emperor reached Koshida village in Soe district, Yamato, and learned that his path was blocked by armed soldiers; he turned back and shaved his head to enter the religious life. Fujiwara no Kusuko committed suicide. (Nihon Kōki (Later Chronicles of Japan) 日本後紀 卷20)
Abe no Kiyotsugu, vice-governor of Echizen, and Kudara-no-Kishi Aisen, provisional junior assistant, heard that the retired emperor was going to Ise; they raised troops in response and captured the new vice-governor Tomi no Fujitsu. Under interrogation they admitted their crimes. (Nihon Kōki (Later Chronicles of Japan) 日本後紀 卷20)
Bohai sent envoys with tribute; the king presented a letter (kei) condoling the death of the former emperor Kanmu and congratulating the accession of the present emperor. (Nihon Kōki (Later Chronicles of Japan) 日本後紀 卷20)
Central Asia (1)
News of the victory reaches Merv; al-Ma'mun is hailed as caliph (Al-Tabari, History of the Prophets and Kings Series III tom.2 (Arg.) [india.history.resource.86977], Annus 195)
News reaches the emperor that 200 Norman ships landed in Frisia, devastated the coastal islands, and after defeating the Frisians three times took 100 pounds of silver. He has the army mustered, crosses the Rhine, and waits for troops at Lippeham. Meanwhile Charles's elephant suddenly dies (Royal Frankish Annals ARF a.810, Kurze 1895 p.131)
The emperor camps where the Aller River joins the Weser to await Godofrid's challenge. But news arrives that Godofrid was killed by his own men, that the fleet had gone home, that the castle of Hohbuoki fell to Vilhi, and that King Pippin of Italy died on July 8 (Royal Frankish Annals ARF a.810, Kurze 1895 p.131)