Fochriw is a typical South Wales Valleys coal mining village that developed from its rural existence by the need for iron and coal during the 19th century. It is located on the north-east flank of Mynydd Fochriw at the head of the Bargoed Fach (now called the Darran) valley, approximately north of Bargoed, and south east of Merthyr Tydfil. The village straddles two ancient hamlets in the parish of Gelligaer, these being the Ysgwyddgwyn and Brithdir hamlets, the dividing line being the brook (Bargoed Fach) which flows in the bottom of the valley. The boundaries of these hamlets were walked by a number of parishioners of the parish on 24th day of May, 1750, and a document detailing the boundaries of each hamlet, namely Keven, Hengode, Garthgynyd, Ysgwyddgwyn, and Brithdecr (Brithdir) was produced, extracts of same are reproduced below.