The Roman departure opened the door for the Anglo-Saxon invasion, which is often regarded as the origin of England and the English people. The Anglo-Saxons, a collection of various Germanic peoples, established several kingdoms that became the primary powers in what is now England and parts of southern Scotland.They introduced the Old English language, which displaced the previous British language. The Anglo-Saxons warred with British successor states in Wales, Cornwall, and the Hen Ogledd (Old North; the Brythonic-speaking parts of northern England and southern Scotland), as well as with each other. Raids by the Vikings were frequent after about AD 800, and the Norsemen took control of large parts of what is now England. During this period several rulers attempted to unite the various Anglo-Saxon kingdoms, an effort that led to the emergence of the Kingdom of England by the 10th century.
In 1066, the Normans invaded and conquered England. There was much civil war and battles with other nations throughout the Middle Ages. The Kingdom of England was a sovereign state until the reign of Richard I who made it a vassal of the Holy Roman Empire in 1194. In 1212 during the reign of his brother John Lackland the Kingdom instead became a tribute-paying vassal of the Holy See until the fourteenth century when the Kingdom rejected the overlordship of the Holy See and re-established its sovereignty. During the Renaissance, England was ruled by the Tudors. England had conquered Wales in the 12th century and was then united with Scotland in the early 18th century to form the Kingdom of Great Britain. Following the Industrial Revolution, Great Britain ruled a worldwide Empire, the largest in the world. Following a process of decolonization in the 20th century the vast majority of the empire became independent; however, its cultural impact is widespread and deep in many countries of the present day.
Archaeological evidence indicates that what was later southern Britannia was colonised by humans long before the rest of the British Isles because of its more hospitable climate between and during the various glacial periods of the distant past. The Sweet Track in the Somerset Levels is the oldest timber trackway discovered in Northern Europe and among the oldest roads in the world, and was built in 3807 or 3806 BC.
The first historical mention of the region is from the Massaliote Periplus, a sailing manual for merchants thought to date to the 6th century BC, although cultural and trade links with the continent had existed for millennia prior to this. Pytheas of Massilia wrote of his trading journey to the island around 325 BC.
Later writers such as Pliny the Elder (quoting Timaeus) and Diodorus Siculus (probably drawing on Poseidonius) mention the tin trade from southern Britain, but there is little further historical detail of the people who lived there.
Tacitus wrote that there was no great difference in language between the people of southern Britannia and northern Gaul and noted that the various nations of Britons shared physical characteristics with their continental neighbours