Caledonia is the Latin name given by the Romans, from 69 to 597 AD, to that land of North Britain, Prydein or Pretania in today’s Scotland. It lay north of their province of Britannia and beyond the frontier of their Empire. The etymology of the name is Pretanic. Its modern usage is as a romantic or poetic name for Scotland as a whole, comparable with Hibernia for Ireland and Brittannia for the whole of England and Wales.
The original use of the name, by Tacitus, Ptolemy, Lucan and Pliny the Elder, referred to the area (or parts of the area) later known as Pictavia, Pictland or Tuath Cruithnech (“Land of the Cruthin”) north of Hadrian’s Wall. The name comes from the large central Pretanic tribe, the Caledonii, one amongst several in the area and the dominant tribe, which would explain the binomial Caledonia/Caledonii. Ptolemy’s account also referred to the Caledonia Silva, an idea still recalled in the modern expression “Caledonian Forest”, although the woods are much reduced in size since Roman times.
According to Historia Brittonum the site of the seventh battle of the mythical Arthur was a forest in what is now Scotland, called Coit Celidon in early Welsh. It was also the home of the legendary Merlin
The exact location of what the Romans called Caledonia in the early stages of Britannia is uncertain, and the boundaries are unlikely to have been fixed until the building of Hadrian’s Wall. From then onwards, Caledonia stood to the north of the wall, and to the south was the Roman province of Britannia (consisting of most of what is now England and Wales). During the brief Roman military incursions into central and northern Scotland, the Scottish Lowlands were indeed absorbed into the province of Britannia, and the name was also used by the Romans, prior to their conquest of the southern and central parts of the island, to refer to the whole island of Great Britain. Once the Romans had built a second wall further to the north (the Antonine Wall) and their garrisons advanced north likewise, the developing Roman-Britons south of the wall had trade relations with the Pretani north of the wall, as testified by archaeological evidence, much of it available at the National Museum of Scotland in Edinburgh.
The name “Scotland” is ultimately derived from Scotia, a Latin term first used for Ireland (also called Hibernia by the Romans) and later for Scotland, the Scoti peoples having originated in Ireland and resettled in Scotland. Another, post-conquest, Roman name for the island of Great Britain was Albion, which is cognate with the Scottish Gaelic name for Scotland: Alba.
The name of the Caledonians may be found in toponymy, such as Dùn Chailleann, the Gaelic word for the town of Dunkeld meaning “fort of the Caledonii”, and in that of the mountain Sidh Chailleann , the “fairy hill of the Caledonians”.