Following the virtual abandonment of the Roman city, the area's strategic location on the River Thames meant that the site was not deserted for long. From the late 5th century, Anglo-Saxons began to inhabit the area.
There is almost no reliable evidence about what happened in the London area during the Sub-Roman "Dark Age" period from around 450 AD to 600 AD. Although early Anglo-Saxon settlement avoided the area immediately around Londinium, there was occupation on a small scale of much of the hinterland on both sides of the river. There is no contemporary literary evidence, but the area must for some time have been an active frontier between Saxons and Britons.
Instead, by the 7th century a village and trading centre named Lundenwic, was established approximately one mile (1.6km) to the west of Londinium (named Lundenburh or "London Fort" by the Saxons). Probably using the mouth of the River Fleet as a trading ship and fishing boat harbour.
Lundenwic in the early eighth century, was described by the Venerable Bede as "a trading centre for many nations who visit it by land and sea". The word "wic" was an Old English word for 'trading town' , so Lundenwic literally meant 'London trading town'.
Archaeologists were for many years puzzled as to where early Anglo-Saxon London was located, as they could find little evidence of occupation within the Roman city walls from this period. However in the 1980s it was 'rediscovered' after extensive excavations were reinterpreted as of an urban character by archaeologists Alan Vince and Martin Biddle working independently . Recent excavations in the Covent Garden area have uncovered the extensive Anglo-Saxon settlement dating back into the 7th century. The excavations show that the settlement covered about 600,000 square metres, stretching from the present-day National Gallery site in the west to Aldwych in the east.
By about 600 AD Anglo-Saxon England had become divided into a number of small kingdoms (see Heptarchy) From the mid-6th century, the London area was incorporated into the East Saxons kingdom, which extended as far west as St Albans and included all of later Middlesex, and probably Surrey too for a time.
In 604 Saeberht of the East Saxons converted to Christianity and London received Mellitus, its first post-Roman bishop. At this time Essex owed allegiance to the Bretwalda Ethelbert of Kent, and it was under Ethelbert that Mellitus founded the first St. Paul's Cathedral, traditionally said to be on the site of an old Roman Temple of Diana (although Christopher Wren found no evidence of this). This would have only been a modest church at first and may well have been destroyed after he was expelled from the city by Saeberht's pagan successors in 616. Christianity did not return until around 675 when Theodore of Tarsus installed St Eorconweald as bishop.
The new town came under direct Mercian control in c.670 as the East Saxon kingdom of which it had once been part was gradually reduced in size and status. After the death of the Mercian king Offa in 796, control of London was disputed between Mercia and Wessex.
Attacks from Vikings became increasingly common from around 830 onwards. London was attacked in 842 in a raid that was described by a chronicler as the "great slaughter". In 851 another raid on London, reputedly involving 350 ships, came to plunder the city.
In 865 the Viking "Great Heathen Army" launched a large scale invasion of East Anglia and soon overran East Anglia, Mercia and Northumbria and came close to controlling most of England. By 871 they had reached London, and are believed to have camped within the old Roman walls during the winter of that year. Although it is unclear what happened during this time, London may have come under Viking control for a period.
In 878 however, English forces led by King Alfred the Great defeated the Vikings at the Battle of Edington and forced the Viking leader Guthrum to sue for peace. The Treaty of Wedmore and the later Treaty of Alfred and Guthrum divided England into Alfred's Saxon controlled kingdom and Danish controlled Danelaw.
As the focus of the city was moved back to within the old Roman walls, the older settlement of Lundenwic was largely abandoned and gained the name of Ealdwic or "old settlement". The name survives today as Aldwych.
Alfred appointed his son-in-law Earl Aethelred of Mercia, who was the heir to the destroyed Kingdom of Mercia, as Governor of London and established two defended Boroughs to defend the bridge which was probably rebuilt at this time. The southern end of the Bridge was established as the Borough of Southwark or Suthringa Geworc (defensive work of the men of Surrey) as it was originally known. From this point, the City of London began to develop its own unique local government.
After Aethelred's death, London came under the direct control of English kings. The Kingdom of England established by Alfred was expanded by his son Edward the Elder who won back much land from Danish control. By the early 10th century London had become an important commercial centre. Although the capital of the Kingdom of England was in Winchester, London became increasingly important as a political centre. King Aethelstan held many Royal Councils in London and issued laws from there. King Aethelred the Unready favoured London as his capital and issued the Laws of London there in 978.
It was during the reign of Aethelred that Viking raids began again, led by King Sweyn Forkbeard of Denmark. London was attacked unsuccessfully in 994, but numerous raids followed. By 1013 London underwent a long siege and Aethelred fled abroad. King Sven died but his son Canute continued the attacks, and the following year overran the city.
Aethelred returned with his ally Olaf of Norway to reclaim London. A Norse saga tells of a battle during the Viking occupation where Aethelred returned to attack Viking-occupied London. According to the saga, the Danes lined London Bridge and showered the attackers with spears. Undaunted, the attackers pulled the roofs off nearby houses and held them over their heads in the boats. Thus protected, they were able to get close enough to the bridge to attach ropes to the piers and pull the bridge down, thus ending the Viking occupation of London. There is some speculation that the nursery rhyme "London Bridge is falling down" stems from this incident.
Following Aethelred's death in 1016, his son Edmund Ironside was declared king. The Vikings however returned and again placed London under siege. Initially the city's defenders were able to hold back the invaders. However, Edmund was eventually forced to share power with Canute. When Edmund died Canute became the sole King of England. After two short lived Danish kings, (Harold Harefoot and Harthacanute) the Saxon line was restored when Canute's stepson Edward the Confessor took up the throne in 1042.
Following Edward's death, no clear heir was apparent, and his cousin, Duke William of Normandy, claimed the throne. The Royal Council, however, met in the city and elected the dead King's brother-in-law, Harold Godwinson as King. He was crowned in Westminster Abbey. William, outraged by this, then sent an army to invade England.