Complex sentence: Ferns is a diocese in south-eastern Ireland (province of Leinster; roughly coterminous with County Wexford), founded by St. Aidan or Maedoc.
Split into simpler sentences: Ferns is a diocese in south-eastern Ireland (province of Leinster; roughly coterminous with County Wexford). It was founded by St. Aidan or Maedoc.