Milesians, in Celtic Irish Mythology, are the last of the six tribes to invade and occupy the island of Ireland. As such, this means they are the ancestors of the Celtic Irish people.

Milesians
The Milesians were a pseduo-mythical race of people that were said to inhabit Ireland. Their origin was the northwest of the Iberian Peninsula. In modern day terms, this would be the area around Galicia and Asturias in Spain. The primary reference to this group, as well as the other six tribes of Ireland, all come from the Book of Invasions. This book was an 11th century manuscript said to be based on older sources. The book outlines the various races that were said to have inhabited Ireland.
They were said to be descented from Míl Espáine (Milesius), who himself was said to have been a descendant of Japheth, one of the sons of Noah, and to have lived in Egypt at the time of Moses. Through this supposed lineage, we can see how the writers of the Book of Invasions were heavily influenced by Christian theology.
Arrival and Conflict
According to the Book of Invasion, the Milesians sailed to Ireland in three great fleets, led by each of the three sons of Míl. They encountered the Tuatha Dé Danann, who had supernatural powers and were god-like. The Tuatha Dé Danann had been living in Ireland for many years before the Milesians arrived. There was conflict between the two groups with battles following. There rivalry ended with the Battle of Tailtiu, in which the Milesians emerged victorious.
After the battle, the Milesians divided Ireland into two halves, with Érimón ruling the north and Éber Finn ruling the south. The Milesians brought new culture and a new language to Ireland, the Gaelic language, known today as Irish. Similarly, they are credited with bringing Gaelic culture to Ireland.
Fact or Fiction?
Although the Milesians are considered to be a mythical people as the Book of Invasions is considered to be pseudo-historical, there is some evidence to suggest that they may have been based on real historical occurrenc. Whether the Celtic/Gaelic people arrived via the manner described in the Book of Invasions, there of course was a race of people who did arrive in Ireland and make it the Celtic nation it is today.
Milesians Pronunciation
The pronunciation is Mill-ease-Ian. To hear it spoken, check out the video below
Want to learn more about Celtic Mythology?
There are a number of great books available on Celtic Mythology. This is one of our favourites. It is from a series on Mythology of 8 great race of peoples (Egypt, Celts etc.).