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, Waunhir and the Upper slant; all connected underground and on the surface by a tramway. By 1908, Waunhir and Cadean employed 198 men, while by 1918 the workforce had grown to 435. By 1923 352 men employed at Caedean Slant, Upper Slant employed 63 men and Waunhir 126 men. There were three notable mining accidents:
February 1907, Waunhir slant - 6 men died when a coupling plate broke and full mine-cars ran down the drift - the men had no chance.
1909 - an explosion in the Caedean Slant killed 4 men, possibly caused by firedamp.
26 April 1923- 12 men died whilst travelling out of the mine the end of the day shift, when part of the journey of drams, in which they were riding suddenly careered back down the slope after a connecting shackle broke.
By 1931 the mine was owned by Amalgamated Anthracite Ltd. and employed 700 men on the existing working. These drifts closed in 1934 and was replaced by the Waunffynhonnau drift, which employed over 300 men in 1945. The mine was closed by the National Coal Board in April 1954, with most of the workforce going to Carway or Pentremawr Colliery. The site was later opened up as part of Celtic Energy's move into opencast mining, called Ffos Las, but was closed in 1997. As part of the redevelopment of the site, it has been approved to become a coarse fishing lake, quad bike and mountain biking centre, before proposed redevelopment of the site as a £16 million/1000m horse racing course, training centre and a grandstand for 1,000 spectators. A hotel and up to 250 houses would also be built on the site of the site.
Trimsaran is known for its rugby union involvement, and is a sport that plays a part in the local community. Rugby was first played in Trimsaran in 1910 but the first recorded captain was Bill Bailey in 1927. 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.
