Following the withdrawal of the Roman legions to Gaul (modern France) around 400, the British Isles fell into a very dark period of several centuries from which almost no written records survive. The Roman-British culture that had existed under 400 years of Roman rule disappeared under relentless invasion and migration by barbarians. Celts came over from Ireland (a tribe called the Scotti gave their name to the northern part of the main island, Scotland). Saxons and Angles came from Germany, Frisians from modern Holland, and Jutes from modern Denmark. By 600, the Angles and Saxons controlled most of modern England. By 800, only modern Wales, Scotland, and West Cornwall remained in largely Celtic hands.

The new inhabitants were called Anglo-Saxons (from the Angles and Saxons). The Angles gave their name to the new culture (England from Angle-land), and the Germanic language they brought with them, English, replaced the native Celtic and previously imported Latin. Despite further invasions and even a complete military conquest at a later date, the southern and eastern parts of the largest British Isle have been called England (and its people and language English) ever since.

In 865 the relative peace of England was shattered by a new invasion. Danish Vikings who had been raiding France and Germany formed a great army and turned their attention on the English. Within 10 years, most of the Anglo-Saxon kingdoms had fallen or surrendered. Only the West Saxons (modern Wessex) held out under Alfred, the only English ruler to be called "the Great."

England was divided among the Vikings, the West Saxons, and a few other English kingdoms for nearly 200 years. The Viking half was called the Danelaw ("under Danish law"). The Vikings collected a large payment, called the Danegeld ("the Dane's gold"), to be peaceful. The Danes became Christians and gradually became more settled. In time the English turned on the Danes, and in