'Archaeology Ireland' Heritage Guide number 69: "The Route of An Táin Bó Cúailgne in County Louth", which can be found at the link below, comments on the mythology of Barnavave as follows:

"Barnavave: Having failed to cross the Cronn, Medb’s forces tracked up Glenmore to the river source. The story relates that ‘they would have gone between its source and the mountain only that Medb would not allow it [preferring] that they should go across the mountain so that the track they made might remain there for ever as an insult to the men of Ulster. So they … dug up the earth in front of them (to make a pass through the mountain) which was called Bernas Bó Cúailnge.’ The gap is still there, right on the summit of Barnavave Mountain."

It also seeks to clarify another point of contention regarding Barnavave that you may encounter:
"Most academic writers have equated Bernas Bó Cúailnge with the Windy Gap at the head of Glenmore, but this ignores what the OS maps, farmers and hill-walkers have known for generations: that Barnavave
(Medb’s Gap) is the Bernas Bó Cúailnge (Gap of the Cows of Cooley) of the Táin. The
dramatic but entirely natural fault-line on its summit is visible only from a couple of points on the lowlands, most notably from the village of Grange."

http://louthheritage.ie/publications.shtml Linkback: https://mountainviews.ie/summit/1504/comment/19845/