Before the Germanic invasions
Celts - Prior to the Germanic invasions Britain was inhabited by various Celtic tribes who were united by common speech, customs, and religion. Each tribe was headed by a king and was divided by class into Druids (priests), warrior nobles, and commoners. The lack of political unity made them vulnerable to their enemies. During the first century, Britain was conquered and subjugated by Rome.
Migration of the Germanic speaking people
When Britain gained "independence" from Rome in the year 410ad, the Roman legions withdrew leaving the country vulnerable to invaders. Soon after the withdrawal of Roman troops, inhabitants from the north began attacking the Britons. In response to these attacks, individual towns sought help from the Foedarati, who were Roman mercenaries of German origin, for the defence of the northern parts of England. As the legend has been told, a man named Hengest arrived on the shores of Britain with "3 keels" of warriors in 450ad. This event is known in Latin as the "adventus Saxonum," or the coming of the Saxons. At this time, the Foedarati stopped defending Britain and began conquering the territories on the southern and eastern shores of the country. These invaders drove the Britons to the north and west. The Saxons called the native Britons, 'wealas', which meant foreigner or slave, and from this term came the modern word Welsh. Eight to ten years later many British aristocrats (Celts) and city dwellers began migrating to Brittany, an event known as the second migration.
Although there were many different Germanic tribes migrating to England, several stood out from among the others, such as the Angles, Saxons, Jutes, Frisians, and Franks.The Angles migrated from Denmark and the Saxons from northern Germany. There is some debate as to the exact origin of the Jutes, since linguistic evidence suggests that they came from the Jutland peninsula, while archaeological evidence suggests an origin from one of the northern Frankish realms near the mouth of the Rhine river. The Frisians and Franks migrated mainly from the low countries and north-western Germany.
During the sixth and seventh centuries these Germanic invaders started to carve out kingdoms, fighting both the native Britons and each other for land. First called Saxons, the German invaders were later referred to as Angles, and in the year 601ce the pope referred to Aethelbert of Kent as Rex Anglorum ("king of the Angles"). As time passed, the differences between the Germanic tribal cultures gradually unified until eventually they ceased referring to themselves by their individual origins and became either Anglo-Saxon or English. (map of England 650-750)
As Old English began to evolve, four major dialects emerged which were Kentish, spoken by the Jutes, West Saxon, the Saxon dialect, and Northumbrian and Mercian, subdivisions of the dialect spoken by the Angles. By the 9th century, partly through the influence of King Alfred, the West Saxon dialect became prevalent in literature which aided the dialect's dominance among scholars.
Soon after the Germanic invasions, the inhabitants gave their settlements new names. The most common Saxon place names are those ending in -ton (fenced area), -wick (dwelling), -ham (home), -worth(homestead), -den(pasture), -hurst(wooded hill), and -burn(stream). Some settlement names began with more than one word which either stated personal possession or described a physical description of the area and would later evolve into one word. One example of this evolution would be the word Chatham which was originally Ceatta's Ham (Ceatta's home).
After the conversion of the Anglo-Saxons to Christianity, problems arose with the Celtic Christians (or the Britons). The Celtic church had ceased communication with Roman church for almost two centuries and did not practice the new theological ideas brought to the Anglo-Saxons by Augustine. In particular, they used an older method of calculating the date on which Easter was to be held. Representatives from the two churches met with Oswiu, the king of Northumbria, who was then asked to choose between the two missions. Oswiu chose Rome. Although the Celtic church found favor with some of the later kings, the Roman church was the more dominant of the two. The largest number of Latin words was introduced as a result of the spread of Christianity, such as altar, mass, priest, psalm, temple, kitchen, palm, and pear.
The 8th century and the beginning of the Viking raids - The first major raid by Vikings occurred in the year 793 at the Northumbrian monastery at Lindisfarne. The Vikings would continue major raids along most of the southern and eastern coasts of England for a decade. About 40 Scandinavian (Old Norse) words were introduced into Old English during this period. Words acquired during this period pertained to the sea and the Scandinavian administrative system. Some examples of these borrowings are law, take, cut, anger, wrong, freckle, both, ill, ugly, as well as, the verb form 'are'. They also introduced many new names as they founded new settlements with endings such as -scale, -beck, -by, and -fell. One example of a settlement name would be Portinscale or 'Prostitute's hut'.
English Surnames - Anglo-Saxons distinguished between two people with the same name by adding either the place they came from or the job they did to their first name. Modern surnames such as Baxter, Baker, Weaver, Fisher, Fowler, Hunter, and Farmer are Anglo-Saxon in origin. The Vikings had a different way of distinguishing between people of the same name. They added the name of the person's father or mother to the child's name. As an example, Harald, the son of Erik would be known as Harald Erik's son, or as we would say it today, Harald Erikson. Often Viking families alternated the name of the eldest so that Arn Gunnarsson might be the father and son of Gunnar Arnsson, and the grandfather and grandson of Arn Gunnarson.
The 9th century - During the ninth century, the Danes began a series of major raids on the whole of England. This ended in an agreement which left the Danes in control of half of the country. Alfred the Great eventually fought the Vikings to a standstill at Edington which produced the Treaty of Wedmore in 878ce. This led to an uneasy peace and the establishment of the Danelaw. The fighting would continue, and in 886ce, Alfred captured London from the Danes. The name Engla lande ("the land of the Angles") was used at the end of this century.
Here's a map showing the Anglo-Saxon kingdoms of England.