There was a great war between the Lochlannaich (Scandinavians) and the Irish about Scotland, and the tribute which the Lochlannaich imposed upon Ireland and Scotland both. The cess was hard to bear and grievous to the Irish king.
The Lochlannaich were great strong men and used to come in summer and harvet, eating and spoiling all that the people of the lands were storing up for another year.
The high king in Ireland sent for his advisors seeking a way to drive back the Lochlannaich.
"That will not happen in a day," said one wiseman, "but if you do as I advise, then it will happen in time. Take the biggest men and women that you can find in all of Ireland, marry them one to another, and the seventh generation will settle the matter for you."
This counsel pleased the Irish king and he set the policy forth. All of Ireland was searched for big men and women and a hundred of each were found and married one to another.
The first generation seemed to be too weak, so they married the biggest to each other without regard to kindred - excepting only that they did not marry brothers to sisters. The second generation were not strong enough and, again, they chose the biggest to marry together.
The third generation was stronger and the fourth stronger still. But when it came to the seventh generation, the men were so great and terrible, that they called them "Na Fiantaichean" (meaning "giant heroes", usually written as Fingalians) and also "daoine fiadhaich" (wild/ terrible men). They had yellow hair and it was said of them ...
Fuath na arrachd cha d'theid as
Bho'n Fhéinn àluinn fhalt-bhuidhe.
Ghost nor bogle will not escape
From the beauteous yellow-haired Feinne.
There were 150 of them in that seventh generation and if any person came to them from France or Spain or other relams and they were big, strong, stout men, then the Fingalians took them under their flags and the band entire was called "An Fhéinn".
When the Feinn arrived in Scotland and met with the Lochlannaich, it was the Lochlannaich who fled to their ships in fear.
There were twelve families (households) in Fionn's household and twelve hearths to each household and a man and five score warriors about each hearth. Where did they all go; none ever knew, excepting those whose deaths are known; such as Goll, Osgar, Diarmaid, etc. Fionn, himself, was never slain, but he lies with the rest. Caoilte was not killed but Ossian was the last of the Feinne and it was he who told Padruig (St. Patrick) the tales of their lives.
They all went away in a single day.
It is believed that they lie at rest somwhere hidden in a cave in the hills, fo gheasaibh - under enchantment. At the mouth of the cave hung a horn which if any man ever should come and blow three times, the spell would be broken, and the Feinn would rise alive and well.
It is said that a hunter one day, wandering in the mist, came upon this cave, saw the horn, and knew what it meant. He looked in and saw the Feinn lying asleep all round the cave. he lifted the horn and blew one blast. He looked in again, and saw that the Feinn had awakened, but lay still with their eyes staring, like those of dead men. He took the horn again, blew another blast, and instantly the Feinn all moved, each resting on his elbow, and turned their great cold eyes upon the man. Terrified at their aspect, the hunter turned and fled homewards, hearing behind him a great howling as of deerhounds and a voice crying out, "A dhuine dhona ghòraich, is miosa 'dh'fhàg na 'fhuair thu!" Thou wretched foolish man, that worse left than thou foundest!