From The South Wales Guardian:

“BACK in October 2012 we reported what was initially thought to be a neolithic stone row on Betws Mountain was probably just a relatively modern grazing boundary or route waymarker.
At least that was the conclusion of experts from Cadw after inspecting the find.
But now the goal-posts – sorry, waymarkers – appear to have been moved because a senior Cadw inspector has conceded their initial identification may have been somewhat hasty. This begs the question: if those stones aren’t grazing boundaries or waymarkers, what the heck are they”
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Readers of the Journal are welcome to submit their own ideas on this mystery.
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puzzle

See more here

https://heritageaction.wordpress.com/2014/03/10/a-stone-alignment-at-bancbryn-mynydd-y-betws-carmarthenshire-part-one/