Caledonia, the ancient Roman name for Scotland. The Caledonians (later called Picts), who lived in the Scottish Highlands, were a barbarian people who fiercely resisted Roman invasion. Although defeated in 84 A.D., the Caledonians were so feared that two lines of fortifications—Hadrian's Wall, 122–27, and the Wall of Antoninus, 140–42—were built to protect Roman Britain from them.