Cos. Cavan & Leitrim plus bits of adjoining cos. constituted the area of the Kingdom of Breifne, which was in the early 12th century coextensive with the Catholic Diocese of Kilmore. The goal of this project is to establish Y-DNA profiles for the early Breifne Clans. The O'Rourkes were the kings of Breifne, but were eventually forced to split the kingdom with the O'Reillys. Some other prominent pre-14th century clans were MacBrady, Magauran/McGovern, MacKiernan, O'Donohoe, O'Farrelly, MacIlduff, O'Boylan, O'Drum, O'Meehan, MacGoldrick, MacClancy, O'Curneen, MacConsnave (Ford), O'Mulvey, MacRannall (Reynolds), MacShanly etc. Some later arrivals were O'Clery (Clarke), O'Curry, MacCabe, Donaghy, MacDonough, MacGuire, MacManus etc. MacGowan (Smith) probably had multiple origins. Preliminary results for the Donohoes indicates that outside lineages of the same name came into Breifne, but it is not yet known if that is also true of other surnames of the area.