As the youngest of twelve brothers, Brian was highly unlikely to be heir to his father's throne. When he was young, he was sent to a monastery to study Latin and the history of Ireland. He was taught at the monastery on the island of Inisfallen, near modern Killarney in County Kerry. His teacher or mentor was the noted monk, Maelsuthain Ua Cearbhaill, an Eóganacht chief who had become the head of the monastery, noted for starting the Annals of Inisfallen. Ua Cearbhaill would later become Brian's "anmchara" (advisor). However, when Brian was ten years old, he received news that his father had been killed in battle with the Vikings of Limerick, and he was brought home.