Mythic History: Irish Conquests
The following is a brief and less detailed summary of information on the peopling of Ireland by mythic races in ancient antiquity. This particular summary is derived from the book Celtic Myths & Legends by T.W. Rolleston, which is it's self a briefer summary and compilation of various celtic myth cycles.
The Partholanians came to Ireland from the west (the region of the dead) and found the Formorians whom they drove out to the northern seas (occasionally the Formorians come back to cause trouble though). During this time many topographical features were added to the land. Then the Partholanians were afflicted with a pestilance and gathered at a plain of Senmag to die together.
The Nemedians came next, somewhat related to the Partholanians. They also fight with and defeat the Formorians in several battles but then are in turn decimated by a plague. From their island the Formorians exact a tribute of 2/3 the produce and children of the land. The Nemedians eventually rise up again and revolt and capture the Formorian's island but then a fresh host of Formori arive and route them utterly.
Only 30 Nemedians survive and leave Ireland. By some accounts these found Great Britan and/or are the ancestors of the Firbolgs and the Tuatha De Danann.
The Firbolgs apparently weren't originally from Greece but settled there for awhile and were forced by the people there to cart fertile dirt to the tops of hills in leather bags, though this may be an invention of later eras to account for their name which means "men of bags". In time they grew tired of their oppression and reshaped their bags into coracles and sailed away. By other accounts they originate from Spain.
There were three tribes of Firbolgs: the Fir-Bolg, the Fir-Domnan, and the Galioin. Little else is said of the Firbolg except regarding their conflict with the Tuatha De Danann.
The Tuatha De Danann (or Danaan) were the "people of the god whose mother is Dana". In the druidic conception these were associated with truth, light, and beauty (though in the popular conception they may have also been linked with forces of the earth). The Danaan agreed to share Ireland with the Firbolg but the Firbolg rejected the offer. In the ensuing war the Danaan employed the magic, healing, and other arts and sciences displaying a clever degree of technical sophistication, while the Firbolg relied more heavily on brute strength. As a result the Firbolg were defeated, though allowed to remain and inhabit the provence of Connacht.
The Danaan remain and have a much more interesting and extensive history, also comming into conflict with the Formorians, until the comming of the Milesians (sons of Miled).
The Milesians arrive from Spain (which is sometimes also associated with the land of the dead) and are more associated with mortal humans. After conflicts of magical and mundane nature the Milesians defeat the Danaan. But the Danaan are not driven out of Ireland, rather they split the physical and spiritual aspects of the land, dwelling invisibly in the spiritual aspect while leaving the physical to the conquerers.
