It is this Crimthann who took the fortress of Doire Da Broc from the sons of Eochaid Mugmeadhon (of the kings of Tara) ie., from Brian, Fiachra, Oilill and Feargus. Crimthann's sister Muingfionn was mother of those four sons. So that her son, Brian, would get the kingship of Ireland, she plotted to poison her brother, Criomthann; the latter died of that poisonous drink; and Mungfionn herself died as well at Inish Donglais on the Moy (Co. Mayo) - as she tasted the drink in order to induce her brother to drink from it. Crimthann having drunk it came to Sliabh Uidhe on Riogh "The Mountain of the King's Death" (now Cratloe Hill, Co. Clare) and there expired.226