"Gwregys Gareth"

Translation: Gareth's belt

[AnUnicorn]

So if you see two nouns in a row in Welsh, it's always a genitive construction and it's [thing] [possessor]?

Like "cat food" -> "food [of] cat" -> bwyd cath?

[EllisVaughan]

Yes, at least I can't think of an example that contradicts that.