This song is a window into the distant past, the world of Celtic warriors and the bards who sang of their heroic deeds in torchlit halls. It's the most obscure surviving genre of Gaelic song, preserved only by a tiny handful of mostly elderly singers. The genre is known as “Ossianic chanting.” Most (but not all) Ossianic chants tell the stories of the Fianna warriors of ancient Irish and Scottish legend. When you listen to one of these chants, you're listening to the Gaelic equivalent of the wandering Homeric bards who sang the Iliad and Odyssey centuries before they were ever written down.
Unlike the vast majority of “Celtic music,” these chants are genuinely old enough to be directly related to the world of the ancient Celts. Based on the language in the chants, they were most likely composed in the early Middle Ages, but the tradition in which they were composed is very much older. A bard of the ancient Picts or Gauls would surely recognize these songs as being part of his own tradition.
There's something faintly spooky about hearing a song so ancient and knowing that the very same song was one performed in the halls of tribal chieftains for the entertainment of warriors and heroes. Ossianic chant is nearly dead as a song tradition even among the Gaels- but it is not dead yet. Maybe with a little luck, it will continue to live on, a link in a chain so long we can't even say where it really began.