There have been men in the Darran Valley area since the Stone Age. Evidence of a settled community on the slopes of the Graig from the 5th to the 16th century was discovered in the 1930’s.
The first community of any size to establish itself took its name from the then biggest farm and was known as Ysgwyddgwyn.
In 800 there were about 100 inhabitants. By 1900, the population had grown to 2,500. When the railways came in the second half of the 19th century, the name Ysgwyddgwyn was changed to Deri – the Welsh word for oak trees.
The two dominating influences on the life of the people of the Darran Valley through the ages have been Christianity and coal – between them, they have affected the well-being of every one if its ihnabitants in one way or another. Christianity first came with St Gwladys in the 5th century. Modern religious influences came in force to the village with the expansion of the Welsh non-conformist movement in the 19th century.
The coal industry in the valley started in 1833 when the first seam of coal – the celebrated Brithdir seam – was exploited. The modern coal mine came to Deri when the first vertical shaft was dug in 1864. The language of the original inhabitants was Welsh – a language with its roots in the ancient Brythonic spoken by early settlers from Ireland. Increasing industrial activity in the 19th century brought into the area a considerable number of “foreigners” – English speaking men and women from all over the British Isles. The influx of strangerswas so great that, by 1905, the number of non-Welsh-speaking Deri people had so increased that a special chapel was built for them near the first one, erected for the Welsh-speaking population in 1865.
The social upheaval and the rise of the Labour party at the start of the 20th century had its repercussions. The First World War took its toll of Deri people as it did for most other villages throughout the land. The General Strike of 1921 and the big Lock-out of 1926 caused untold hardship. For years the Darran Valley was part of the great depression of the 20’s and the 30’s. With the advent of the Second World War, the economic gloom was lifted somewhat although, once again, Deri men and women became casualties on battlefields all over the world.