Complex sentence: In the Early Medieval period Rathmore was a stronghold of the Meic Bráenáin, a branch of the Fothairt Airthir Life and was located within the Fothairt Airthir Life territory of "Uí Máel Ruba" or "Uí Maíleruba".
Split into simpler sentences: In the Early Medieval period Rathmore was a stronghold of the Meic Bráenáin, a branch of the Fothairt Airthir Life. It was located within the Fothairt Airthir Life territory of "Uí Máel Ruba" or "Uí Maíleruba".