Middle Irish

Middle Irish is the name given by historical philologists to the Goidelic language spoken in Ireland, Scotland and the Isle of Man from the 10th to 12th centuries; it is therefore a contemporary of late Old English and early Middle English. The modern Goidelic languages, Irish, Scottish Gaelic, and Manx, are all descendants of Middle Irish.

At its height, Middle Irish was spoken throughout Ireland, Scotland and the Isle of Man; from Munster to the island of Inchcolm in the Firth of Forth. Its geographical range made it the most widespread of all Insular languages before the late 12th century, when Middle English began to make inroads into Ireland, and many of the Celtic regions of northern and western Britain.

Few medieval European languages can rival the volume of literature extant in Middle Irish. Much of this survival is due to the tenacity of a few early modern Irish antiquarians, but the sheer volume of sagas, annals, hagiographies, and so forth, which survive shows how much confidence members of the medieval Gaelic learned orders had in their own vernacular. Almost all of it survives in Ireland; very little survives in Scotland or Man. The Lebor Bretnach, the "Irish Nennius", survives only from manuscripts preserved in Ireland; however, Thomas Owen Clancy has recently argued that it was written in Scotland, at the monastery in Abernethy.