Book of Dinnseanchas

The Book of Dinnseanchas was originally composed in the sixth century by Amergin, chief bard to the monarch Dermod, at Tarah; but many additions have been made to it by later writers. This celebrated work gives an account of noted places, as Fortresses, Raths, Cities, Plains, Mountains, Lakes, Rivers, etc., and of the origin of their names; and contains much interesting information on ancient Irish history and topography.