In 787 the Second Council of Nicaea ends the first iconoclastic period in the Byzantine Empire.
The earliest date given for a Viking raid is 787 AD when, according to the Anglo-Saxon Chronicle, a group of men from Norway sailed to Portland, in Dorset. The first three Viking ships landed in Wessex and the Norsemen started to plunder towns and coastal monasteries. The next recorded attack, dated June 8, 793 AD, was on the monastery at Lindisfarne – the "Holy Island" – on the east coast of England. In 793 Irene orders her son, the Byzantine emperor Constantine VI captured and deposed. A solar eclipse and a darkness of seventeen days' duration were attributed by the common superstition to the horror of heaven. However, modern research suggests that Constantine's wounds were not fatal and that he actually outlived his mother. Irene reigned in prosperity and splendour for five years. However, Irene's triumph did have consequences. She restored monasteries and since was among the saints of the Eastern Orthodox church. Pope Leo III, who needed help against enemies in Rome and who saw the throne of the Byzantine emperor as vacant (lacking a male occupant), crowned Charlemagne the Holy Roman Emperor in 800.
The first book Gesta gives a history from 788 onwards of the Church in Hamburg-Bremen, and the Christian mission in the North. It consists of four volumes about the history of the archbishopry of Hamburg-Bremen, and the isles of the north. The works of Adam of Bremen, the medieval chronicler is based on the church library of Bremen with possible historical themes of various bishoprics. The fourth book is also the first known European record that mentions Vinland, a land centuries later known as North America, completed in 1075.
By the mid 9th century, there were Viking attacks on the coastal Kingdom of Asturias in the far northwest of the peninsula and by the reign of Alfonso III. Vikings were stifling the already weak threads of sea communications that tied Galicia (a province of the Kingdom) to the rest of Europe. After Tuy was sacked early in the 11th century, its bishopric remained vacant for the next half-century. Many rune stones in Scandinavia record the names of participants in Viking expeditions. Other rune stones mention men who died on Viking expeditions, among them the around 25 Ingvar stones in the Mälardalen district of Sweden erected to commemorate members of a disastrous expedition into present-day Russia in the early 11th century.
In A.D. 793, the Vikings raid on Lindisfarne made their presence known to the powerful empires of Europe at the time. After the murder of King Godfred in 810, those who became kings though had to worry of those returning Vikings who often challenged them for power after returning home. Horik, son of Godfred took over in 827 until a civil war which resulted in his death. Details of positions of power are unclear after this until around 900 when Viking raiders returning from Sweden took power. Following this was the Jelling Dynasty, which was ruled by Harold Blåtand (Harold Bluetooth) who claimed to have conquered all of Denmark on the Jelling Stones and claimed Denmark as Christian. The word viking appears on several rune stones found in Scandinavia. In the Icelandic sagas, víking refers to an overseas expedition and víkingr, to a seaman or warrior taking part in such an expedition.