 The "Metrical Dindshenchas", or Lore of Places, a Middle Irish collection of poetry purporting to explain the origins of Irish place names, claims that Mullaghmast is named for Maistiu, wife of Dáire Derg, who was killed by the sorcery of the malicious faery Gris, who was in turned killed by Dáire Derg.A standing stone from Mullaghmast, decorated with a triskele, thought to belong to the very end of the prehistoric period, or perhaps to the early Christian period, is now in the National Museum of Ireland in Dublin.Mullaghmast was the royal residence of the Uí Muiredaig kings (later to become the O'Toole family), a sept of the Uí Dúnlainge dynasty of the Laigin.