Corpus of Electronic Texts Edition
The Second Battle of Moytura (Author: [unknown])

section 78

Then Nuada inquired of the sorcerer whose name was Mathgen, what power he could wield? He answered that through his contrivance he would cast the mountains of Ireland on the Fomorians, and roll their summits against the ground. And he declared to them that the twelve chief mountains of the land of Erin would support the Tuatha Dé Danonn, in battling for them, to wit, Slieve League, and Denna Ulad and the Mourne Mountains, and Bri Ruri and Slieve Bloom and Sliab Snechtai, Slemish and Blai-sliab and Nemthenn and Sliab Maccu Belgodon and Segais and Cruachan Aigle.