In his "History of Mayo" (page 31), Knox writes: "St. Tigernan of Errew worked in Tirawley in the early part of the sixth century.
Errew - Oireadh - is a slender peninsula jutting out from the western shore of Lough Conn.
The present Abbey of Errew seems to have been built in the early-to-mid 12th century "under the influence of the Cistercians, but before Irish architects were familiar with it."
This abbey appears to have been the ecclesiastical head of the Ó Lactna lordship of An Bac and Glen Nephin.
Gilla Áedha Ua Maigín, Bishop of Cork (died 1172), is noted in the Annals of the Four Masters as "of the family of Errew of Lough Con."