I found a book called The Religion of the Ancient Celts. p.50-53. I posted the book Tephi Part 1 and the tribe that after our DNA part 2
https://www.globalgreyebooks.com/religion-of-the-ancient-celts-ebook.html -of course they want to write it off as mythology
On page 50-Many mythical elements may therefore be looked for in the euhemerised chronicles of ancient Ireland. But the chroniclers themselves were but the continuers of a process which must have been at work as soon as the influence of Christianity began to be felt. Their passion, however, was to show the descent of the Irish and the older peoples from the old Biblical personages, a process dear to the modern AngloIsraelite, some of whose arguments are based on the wild romancing of the chroniclers. / Various stories were told of the first peopling of Ireland. " Banba, with two other daughters of Cain, arrived with fifty women and three men, only to die of the plague. Three Cy fishermen next discovered Ireland, and " of the island of Banba of Fair Women with hardihood they took possession." Having gone to fetch their wives, they perished in the deluge at Tuath Inba. A more popular account was that of the coming of Cessair, Noah's granddaughter, with her father, husband, a third man, Ladru, " the first dead man of Erin," and fifty damsels. Her coming was the result of the advice of a j laimh-dhia, or " hand-god," but their ship was wrecked, and all save her husband, Finntain, who survived for centuries, perished in the flood. Cessair's ship was less serviceable than her grandparent's Followed the race _of_JPa.T-thoTa,n J " no wiser one than the other," who increased on the land until plague swept them away, with the exception of Tuan mac Caraill, who, after many transformations, told the story of Ireland to S. Finnen centuries after. The survival of Finntain and Tuan, doubles of each other, was an invention of the chroniclers, to explain the survival of the history of colonists who had all perished. Keating, on the other hand, rejecting the sole survivor theory as contradictory to Scripture, suggests that "aerial demons," followers of the invaders, revealed all to the chroniclers, unless indeed they found it engraved with " an iron pen and lead in the rocks."
The Tuatha De Danann arrived from heaven—an idea in keeping with their character as beneficent gods, but later legend told how they came from the north. They reached Ireland on Beltane, shrouded in a magic mist, and finally, after one or, in other accounts, two battles, defeated the Firbolgs and Fomorians at Magtured. The older story of one battle may be regarded as a euhemerised account of the seeming conflict of nature powers. The first battle is described in a fifteenth to sixteenth century MS.,and is referred to in a fifteenth century account of the second battle, full of archaic reminiscences, and composed from various earlier documents.3 The Firbolgs, defeated in the first battle, join the Fomorians, after great losses. Meanwhile Tuada, leader of the Tuatha De - Danann, lost his hand, and as no king with a blemish could sit on the throne, the crown was given to Bres, son of the Fomorian Elatha and his sister Eri, a woman of the Tuatha De Danann.