The River Shannon served as an easy route by which raids could be made against the provinces of Connacht and Meath. Both Brian's father, Cennétig mac Lorcáin, and his older brother Mathgamain had conducted river-borne raids, in which the young Brian would undoubtedly have participated. This may have been the root of his appreciation for naval forces in his later career. Thus, an important influence upon the Dalcassians was the presence of the Hiberno-Norse city of Limerick on an isthmus around which the Shannon River winds (known today as King's Island or the Island Field). The Norse had made many raids themselves from the Shannon, and the Dalcassians likely benefited from some interaction with them, from which they would have been exposed to innovations such as superior weapons and ship design, all factors that may have contributed to their growing power.