Tailtiu was a noble Rígh-bhean, or Queen, of the Fir Bolg, the race of peoples who inhabited Ireland before the coming of the Tuatha De Dannan. Tailtiu was Lugh's foster-mother. His fosterage with Tailtiu begins his intimate experience with the energies of the Land, preparing him as a future champion of the Tribe for a bountiful Harvest.

Tailtiu shines as a goddess with the most supreme of virtues, self sacrifice. Tailtiu gave her life in a most extraordinary way. One year the Fir Bolg had a bad harvest and many were starving. Tailtiu took up an axe and began to clear a forest with her own two hands in the space of one year. Little did the Fir Bolg know that this act would kill her. At the end of her labors it is said:

"Her heart burst in her body from the strain beneath her royal vest."

Before she died she told the Fir Bolg to celebrate her passing every year on the anniversary of her death, the 1st of August:

Long was the sorrow, long the weariness of Tailtiu, in sickness after heavy toil; the men of the island of Erin to whom she was in bondage came to receive her last behest. She told them in her sickness (feeble she was but not speechless) that they should hold funeral games to lament her . . . White-sided Tailtiu uttered in her land a true prophecy, that so long as every prince should accept her, Erin should not be without perfect song.

It was Lugh who held the very first Óenach Tailtenn or "Tailtiu Games" to remember and honor his foster-mother. The Fair of Tailtiu was a time of peace, first held by the Fir Bolg in their time, by the Tuatha De Dannan after them, and then by the Sons of Míl until the coming of the Adzehead:

A fair with gold, with silver, with games, with music of chariots, with adornment of body and of soul by means of knowledge and eloquence. A fair without wounding or robbing of any man, without trouble, without dispute, without raping, without challenge of property, without suing, without law-sessions, without evasion, without arrest.

Tailtiu is a reminder of how much the Land gives to us, and the Óenach Tailtenn a time to remember her sacrifice for the fertility of the Land, and how much she gave in return for that boon.