[1] The opposing sides comprising the Fomorians, led by Cichol Gricenchos, and the followers of Partholón.
According to the Lebor Gabála Érenn, the Fomorians had lived in Ireland for 200 years, subsisting by fishing and fowling, before the arrival of Partholón, whose people were the first in Ireland to build houses and brew ale.
The Lebor Gabála dates Partholón's arrival in Ireland to AM 2608 (2590 BCE), and says the Battle of Mag Itha took place ten years later, in AM 2618 (circa 2580 BCE).
The earliest recensions of the Lebor Gabála say that Cichol was killed and the Fomorians destroyed; later recensions say the Fomorians had one arm and one leg each, the battle lasted a week, and no-one was killed or wounded as it was fought by magic.
[3] Geoffrey Keating's Foras Feasa ar Éirinn also mentions the battle, but gives little detail and no date.