There are historical reports of mining activities taking place in the Trimsaran area dating back hundreds of years.

By 1896, the Inspector of Mines noted that Trimsaran employed 144 men, producing coal, anthracite, and fireclay.

By the early 1900s, three drift mines made up Trimsaran colliery: Caedean (deepest), Waunhir and the Upper slant; all connected underground and on the surface by a tramway.

The site was later opened up as part of Celtic Energy's move into opencast mining, called Ffos Las, but was closed in 1997.

Players who have graduated from Trimsaran RFC onto represent Wales included Jonathan Davies, Garan Evans, Aaron "Girthy" Bowen and Gareth Lewis, who made his debut against Australia in the 2016 Autumn internationals.