The Llanelly Railway and Dock Company, opened its line from Pontardulais to Cwmamman on 10th April, 1840.
The railway was extended to Gwaun Cae Gurwen on 6th May, 1841. The track followed the River Garnant up the valley and climbed a steep hill (gradient 1 in 4.9), approximately 132 yards (or metres) long, before reaching the village. The line served two collieries on the way, one by an incline on the south side of the valley.
In June, 1842, Garnant became a junction, when a railway line was opened from there to Brynamman.
The opening of the railway proved to be a major boost to the industrial development of the area, with numerous small pits being opened at the upper end of the valley. By the late nineteenth century, there were a substantial number of colliers employed at Blaengurwen, Cwm-teg and Pantycelyn, and further pits were opened at Maerdy in 1886, Cwmgors in 1887 and the East Pit in 1910.