7 events the sources record for this year, grouped by region.
What happened
China (2)
Wei Gao defeated the Tibetans in the valley north of Taideng and recovered Xi Prefecture. (New Book of Tang (Xin Tangshu), Annals 新唐書 卷007 德宗·順宗·憲宗 貞元5年9月)
Wei Gao crushes the Tibetan military governors of Qinghai and Lacheng at Taideng Valley in Xizhou. (Zizhi Tongjian (Comprehensive Mirror) 資治通鑑 卷233)
By imperial decree the great commander of the East is rebuked: the government troops have stayed at the Koromo River for over thirty days without advancing. (Shoku Nihongi (Continued Chronicles of Japan) 續日本紀 卷第40 「五月癸丑。勅征東將軍」)
The great commander of the East reports that the middle and rear troops, two thousand each, crossed the river and reached the dwelling of Aterui (阿弖流爲), where more than 300 enemies met them in battle. (Shoku Nihongi (Continued Chronicles of Japan) 續日本紀 卷第40 「六月甲戌。征東將軍奏」)
Ki no Kosami, great commander holding the sword for the conquest of the East, returns from Mutsu and hands back the sword of authority. (Shoku Nihongi (Continued Chronicles of Japan) 續日本紀 卷第40 「九月丁未。持節征東大」)
Western Europe (1)
To punish the Slavs of the Wilzi, Charles crosses the Rhine at Cologne and passes through Saxony; he builds two bridges over the Elbe, crosses, and devastates Wilzi land. Dragovit surrenders with hostages and an oath of loyalty, and other Slav chiefs also yield (Royal Frankish Annals ARF(Einhard판) a.789, Kurze 1895 p.85)