Europe

• Bulgaria
  First Bulgarian Empire
  The First Bulgarian Empire was a medieval Bulgarian state founded in the north-eastern Balkans in c. 680 by the Bulgars, uniting with seven South Slavic tribes...
  
   and the Byzantine Empire
  Byzantine Empire
  The Byzantine Empire was the Eastern Roman Empire during the periods of Late Antiquity and the Middle Ages, centred on the capital of Constantinople. Known simply as the Roman Empire or Romania to its inhabitants and neighbours, the Empire was the direct continuation of the Ancient Roman State...
  
   sign the Treaty of 815
  Treaty of 815
  The Treaty of 815 was a 30-year peace agreement signed in Constantinople between the Bulgarian Khan Omurtag and the Byzantine Emperor Leo V the Armenian.- Background :...
  
   in Constantinople
  Constantinople
  Constantinople was the capital of the Roman, Eastern Roman, Byzantine, Latin, and Ottoman Empires. Throughout most of the Middle Ages, Constantinople was Europe's largest and wealthiest city.-Names:...
  
  .
• Egbert of Wessex
  Egbert of Wessex
  Egbert was King of Wessex from 802 until his death in 839. His father was Ealhmund of Kent...
  
   ravages the territories of the west Welsh (Cornwall
  Cornwall
  Cornwall is a unitary authority and ceremonial county of England, within the United Kingdom. It is bordered to the north and west by the Celtic Sea, to the south by the English Channel, and to the east by the county of Devon, over the River Tamar. Cornwall has a population of , and covers an area of...
  
  ).

Asia

• In South Central Chang'an, the capital city of the Chinese Tang Dynasty
  Tang Dynasty
  The Tang Dynasty was an imperial dynasty of China preceded by the Sui Dynasty and followed by the Five Dynasties and Ten Kingdoms Period. It was founded by the Li family, who seized power during the decline and collapse of the Sui Empire...
  
  , assassin
  Assassination
  To carry out an assassination is "to murder by a sudden and/or secret attack, often for political reasons." Alternatively, assassination may be defined as "the act of deliberately killing someone, especially a public figure, usually for hire or for political reasons."An assassination may be...
  
  s murder Chancellor Wu Yuanheng
  Wu Yuanheng
  Wu Yuanheng , courtesy name Bocang , formally Duke Zhongmin of Linhuai , was an official of the Chinese dynasty Tang Dynasty, serving as a chancellor during the reign of Emperor Xianzong...
  
   at a city ward gate on a day just before dawn.

Deaths

• June 2 – Saint Nicephorus, patriarch of Constantinople
  Patriarch of Constantinople
  The Ecumenical Patriarch is the Archbishop of Constantinople – New Rome – ranking as primus inter pares in the Eastern Orthodox communion, which is seen by followers as the One, Holy, Catholic, and Apostolic Church....
  
  
• Abu Musa Jabir Ibn Hayyan (Geber), Muslim alchemist
  Alchemy
  Alchemy is an influential philosophical tradition whose early practitioners’ claims to profound powers were known from antiquity. The defining objectives of alchemy are varied; these include the creation of the fabled philosopher's stone possessing powers including the capability of turning base...
  
   (approximate date)
• Abu Nuwas
  Abu Nuwas
  Abu-Nuwas al-Hasan ben Hani Al-Hakami ,a known as Abū-Nuwās , was one of the greatest of classical Arabic poets, who also composed in Persian on occasion. Born in the city of Ahvaz in Persia, of an Arab father and a Persian mother, he became a master of all the contemporary genres of Arabic poetry...
  
  , Arab poet