Christianity came to Wales by two routes. It was first introduced by the Romans during the time Wales was part of the Roman Empire. Then during the early 5th century AD, it was re-invigorated by missionaries travelling along the western sea route which linked Wales with Ireland, Cornwall, Brittany and Scotland.

These pioneering Christians were monks and some lived as hermits, which meant that they deliberately chose to live in isolation from other people. Others set up churches on coasts or islands close to the shore. The settlements that grew up around the churches resembled traditional British villages and many of them have stone crosses of this period with Christian symbols carved upon them.

Men like Saint Beuno in Gwynedd and Saint Cadoc in south-east Wales were greatly revered and churches were dedicated to them after their death. Saint David (Dewi), the patron saint of Wales, was a charismatic abbot who lived from about 530-589. He founded a monastery at Glyn Rhosyn (modern St David’s), in south-west Wales. Later a cathedral was built on the site which became a popular place for pilgrimage, especially after 1120, when David was recognised as a saint.