Great Britain became an island at the end of the last glacial period when sea levels rose due to the combination of melting glaciers and the subsequent isostatic rebound of the crust.Great Britain's Iron Age inhabitants are known as Britons; they spoke Celtic languages.
In the course of the 500 years after the Roman Empire fell, the Britons of the south and east of the island were assimilated or displaced by invading Germanic tribes (Angles, Saxons, and Jutes, often referred to collectively as Anglo-Saxons).
After the Anglo-Saxon period, Britain was used as a historical term only.
Geoffrey of Monmouth in his pseudohistorical Historia Regum Britanniae (c.
The oldest mention of terms related to Great Britain was by Aristotle (c.
384–322 BC), or possibly by Pseudo-Aristotle, in his text On the Universe, Vol. To quote his works, "There are two very large islands in it, called the British Isles, Albion and Ierne". AD 23–79) in his Natural History records of Great Britain: "Its former name was Albion; but at a later period, all the islands, of which we shall just now briefly make mention, were included under the name of 'Britanniæ.'" The name Britain descends from the Latin name for Britain, Britannia or Brittānia, the land of the Britons.