It was the market town for the scattered agricultural communities in the broad, fertile countryside to the south and the rich landowners with extensive holdings in the uplands to the east, the home of many sheep and few people.

To the north was Cors Caron which was a fertile land when drained, and to the west a hilly region with self-sufficient farmers on smallholdings of a few acres.

These people all converged on Tregaron for the weekly market and the annual fair, Ffair Garon, where the sale of poultry, pigs, cattle and horses took place.

[7]: p240 Tregaron was a main gathering place for the drovers who, before the advent of rail transport, herded large numbers of cattle, sheep and even geese hundreds of miles to the markets of southeast England.

Woollen socks were knitted at home by men, women and children and sold at the market, often to dealers who resold them in the industrial valleys of South Wales.

He was a man of lowly origins but "his courage and generous deportment obtained him the sovereignty in Wales: he made war against the Romans, reigned seven years and was buried in Tregarron".

According to Geoffrey of Monmouth in the translation from Welsh "there was a young man of the name of Caron, of a British family, but of low degree, who... went to Rome, and solicited the Senate to grant him permission and aid to protect the sea coasts of Britain... [He] proposed to the Britons that they should make him king... Allectus with three legions... overpowered him..."[8] An early Christian stone slab bearing the name Carausius and the Chi Rho symbol is preserved in Penmachno.

In March, 1977, a cottage near Tregaron was one target of an Operation Julie police raid in which vast quantities of the drug LSD were seized.

[15][16] The town holds an annual festival of harness racing in August, which attracts racegoers from across the UK; this was started in 1980 by the Tregaron Trotting Club.

At the urging of local people, led by David Davies and supported by Joseph Jenkins, capital was subscribed for a station at Tregaron.

[21]: pp 79  In 1965, Tregaron's train service was withdrawn and the station closed, after the line was badly damaged by flooding south of Aberystwyth.