[citation needed] On the death of the previous chief, his uncle Tomás Mág Tighearnán in 1358, Brian took the chieftaincy and resided in the castle of Croaghan of the Cups (Irish- Cruachan O'Cúbhrán), now in the townland of Coolnashinny, besides the modern town of Killeshandra.
The Annals of Ulster for 1362 state Brian, son of Matthew Mag Tigernain, the son of a chief of greatest felicity and pre-eminence, general patron respecting food and cattle, died about the feast of Saint James July 25 that year, as the poet said: Brian Mag Tigernain of the contests, With his hospitality comparison were not just He practised hospitality without reward, Heaven was the end of his battle-career.
The Annals of the Four Masters for 1365 state- Brian, the son of Matthew Mac Tiernarn, Chief of Teallach Dunchadha, the most distinguished for valour, renown, fame, and power, of the sub-chieftains of Breifny, died.
The Annals of Connacht for the year 1365 state- Brian son of Matha Mag Tigernain, chieftain of Tullyhuncoe, the most famous man of the Brefnians, died.
The Annals of Loch Cé for the year 1365 state- Brian, son of Matthew Mac Tighernain, chieftain of Tellach-Dunchadha, the most famous man of the Breifnians, mortuus est, ut dicitur— Brian Mac Tighernain of the conflicts With his hospitality comparison was not just He followed generosity without hatred; Heaven was the end of his battle-career.