Complex sentence: Thus the area became known as Cwmparc and its stream Nant Cwmparc (Cwm being the Welsh for valley), with the development of the coal mining village in this part of the South Wales Valleys in the 19th century the village also became known as Cwmparc.
Split into simpler sentences: Thus the area became known as Cwmparc and its stream Nant Cwmparc (Cwm being the Welsh for valley). With the development of the coal mining village in this part of the South Wales Valleys in the 19th century, the village also became known as Cwmparc.