In the early 5th century AD Britain fell away from the Roman Empire. Kingdoms emerged in what we now call Wales or Cymru.
Today's western Carmarthenshire was part of the kingdom of Dyfed. Its most famous king was to be Hywel Dda, or Hywel the Good.
But inscribed memorial stones like this support the idea that its early rulers were immigrants from Ireland.
Is the man remembered on this stone the 'bad son of a good king' complained about by Gildas in the 6th century? Experts disagree. But it is a rare and exciting window on a time about which we would love to know more.
The stone is inscribed in two languages that say the same thing. Below the Christian cross, the Latin writing translates as 'the memorial stone of Voteporix the Protector'.
The second inscription is notched along the stone's edge. This is an example of the Ogham alphabet which was invented in Ireland. It calls the man Votecorix, the Irish form of his name.
Our early Christian stones are important. They are some of the best evidence for the time after the Romans left.
Archaeologists and historians are slowly increasing our understanding of these 'Dark Ages', but we still have many unanswered questions.