815

Year 815 was a common year starting on Monday of the Julian calendar, the 815th year of the Common Era and Anno Domini designations, the 815th year of the 1st millennium, the 15th year of the 9th century, and the 6th year of the 810s decade.

Events

Byzantine–Bulgarian Treaty: Emperor Leo V the Armenian signs a 30-year peace agreement in Constantinople with Omurtag, ruler of the Bulgarian Empire. The Rhodope Mountains become the Byzantine border again, and Leo regains its lost Black Sea cities, after the Bulgars have them demolished.
Central America
April 2 - Sihyaj K'in Ich’aak II becomes the new ruler of the Mayan city state of Machaquila in Guatemala after the death of Ochk'in Kaloomte' Aj Ho' Baak, and reigns until early 824.
Europe
Hrafna-Flóki Vilgerðarson sets out from the Faroe Islands and discovers Iceland .
Britain
King Egbert of Wessex ravages the territories of the remaining British kingdom Dumnonia, known as the West Welsh.
Asia
Emperor Saga of Japan is the first sovereign to drink tea, imported from China by monks. The upper classes adopt this beverage for medicinal use.
July 13 - Wu Yuanheng, Chinese chancellor of the Tang Dynasty, is murdered by assassins of warlord Wu Yuanji, in Chang'an.
By topic

Synod of Constantinople: A council led by patriarch Theodotus I, in the Hagia Sophia, reinstitutes iconoclasm.