In the comments thread on the post on seventh-century Chester, the discussion turned to the medieval longbow. I said I thought archery was especially associated with south Wales and that I hadn’t got the reference to hand but would post it when I found it. Well, I have now found the reference I was thinking of. It comes from the Description of Wales, written in the 1190s by Gerald of Wales (also known by his Latin name, Giraldus Cambrensis), and the quote is:
Merionyth, and the land of Conan, is the rudest and least cultivated region, and the least accessible. The natives of that part of Wales excel in the use of long lances, as those of Monmouthshire are distinguished for their management of the bow.--Gerald of Wales, Description of Wales, Chapter VI. Online at Project Gutenberg
Monmouthshire is in south-east Wales, immediately west of the River Wye. See the Wikipedia page on the historic county (not to be confused with the smaller modern county of the same name) for maps showing its location, and see Streetmap UK for an interactive map that will let you zoom in and out to put the location in context.
Gerald was a distinguished churchman, the son of a powerful Norman baron and a princess of Deheubarth (south-west Wales), so he was in a position to have access to accurate information about the Wales of his own time. While it is unlikely that the men of Monmouthshire had a monopoly on archery (or that the men of Meirionydd had a monopoly on the use of long spears, come to that), I see no reason to doubt Gerald’s word for a particular skill being concentrated in a particular region, at least in his own time. Whether that reflects any deep-seated historical tradition or was a relatively recent development is open to interpretation.