Scoti

Scoti or Scotti was a name used by Late Roman authors for the Irish. Scotland was named after Irish settlers from the 5th century on.

An early use of the word can be found in the Nomina Provinciarum Omnium (Names of All the Provinces), which dates to about A.D. 312. This is a short list of the names and provinces of the Roman Empire. At the end of this list is a brief list of tribes deemed to be a growing threat to the Empire, which included the Scoti. There is also a reference to the word in St Prosper's chronicle of A.D. 431 where he describes Pope Celestine sending St Palladius to Ireland to preach "ad Scotti in Christum" ("to the Irish who believed in Christ").

Thereafter, periodic raids by Scoti are reported by several later 4th and early 5th century Latin writers, namely Pacatus,Ammianus Marcellinus,Claudian and the Chronica Gallica of 452. Two references to Scoti have recently been identified in Greek literature (as Σκόττοι), in the works of Epiphanius, Bishop of Salamis, writing in the 370s. The fragmentary evidence suggests an intensification of Scoti raiding from the early 360s, culminating in the so-called "barbarian conspiracy" of 367–8, and continuing up to and beyond the end of Roman rule c. 410. The location and frequency of attacks by Scoti remain unclear, as do the origin and identity of the Gaelic population-groups who participated in these raids. By the 5th century, the Gaelic kingdom of Dál Riata had emerged from Ulster, overtaking parts of western Scotland. As this kingdom grew in size and influence, the name was applied to all its subjects – hence the modern terms Scot, Scottish and Scotland.

...
Wikipedia