Preseli Hills (Mynnydd Preseli) which include at least Carn Goedog, Carn Menyn:
Megalith quarries for Stonehenge's bluestones | Antiquity | Cambridge Core — https://www.cambridge.org/core/journals/antiquity/article/megalith-quarries-for-stonehenges-bluestones/AAF715CC586231FFFCC18ACB871C9F5E

