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Border raids and the coming of Christianity: the emerging nation
| Date | Key events |
| 297 | Earliest mention of Picti, by Roman orator Eumenius. |
| 367 | Picts and Scots coordinate successful attacks across Hadrian’s Wall, eventually repelled by Count Theodosius of Britannia (father of the Roman emperor Theodosius). |
| 383 | Magnus Maximus makes his name fighting the Picts and proclaims himself emperor of Britannia; he is put to death by Rome in 388. |
| 397 | Bishop Ninian (c. 360–432) arrives at Whithorn in Galloway to bring Christianity to the British and Pictish people of southern Caledonia. |
| c.428 | British ruler Vortigern hires Hengest, a German mercenary, to defeat Picts raiding eastern Britannia by land and sea. |
| before 500 | Gaels expand the Irish kingdom of Dál Riata into western Caledonia, where they become known as Scots. |
| 563 | Columba (c. 521–97), exiled from Ireland, arrives on Iona and begins his mission to Dál Riata. |
| 565 | Columba visits new Pictish king Bridei son of Mailcon (r. 565–85) at his stronghold near Inverness. |
| late 6th century | Picts overrun Gaelic Dál Riata. |