"Blaencwm is a village in the county borough of Rhondda Cynon Taf, Wales, lying at the head the Rhondda Fawr valley. Two collieries were opened here during the Industrial Revolution, the Dunraven Colliery in 1865 and the Glenrhondda Colliery in 1911. Both had closed by 1966 ...." wikipedia
Transcript of complete name listing for Treherbert and Ystrad-Rhondda, with the parish and hamlets of Ystradyfodwg, Blaen-y-cwm, Blaen-y-Rhondda, Cwmdare, Cwmpark, Llwynpia, Pen-y-griag, Penyrenglyn, Pentre, Ton-pentre-ystrad, Ton-y-pandy, Treorky, Tynewydd and Tynybedw, from Slaters Directory for 1880.
You can see the administrative areas in which Blaencwm has been placed at times in the past.
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