[7] The settlement of Aberdare dates from at least this period, with the first known reference being in a monastic chapter[clarification needed] of 1203 concerning grazing right on Hirwaun Common.

By the 1840s the parish population was increasing by 1,000 people every year, almost exclusively migrant workers from west Wales, which was suffering from an agricultural depression.

[16] In his controversial evidence to the 1847 Inquiry into the State of Education in Wales (the report of which is known in Wales as the Brad y Llyfrau Gleision, Treason of the Blue Books), the Anglican vicar of Aberdare, John Griffith, stated that the English language was "generally understood" and referred to the arrival of people from anglicised areas such as Radnorshire and south Pembrokeshire.

[19] It is still contended that Griffiths was made vicar of Merthyr in the neighbouring valley to escape local anger,[20] even though it was over ten years before he left Aberdare.

The reports and subsequent defence would maintain the perceptions of Aberdare, the Cynon Valley and even the wider area as proudly nonconformist and defiantly Welsh speaking throughout its industrialised history.

The iron industry began to expand in a significant way around 1818 when the Crawshay family of Merthyr purchased the Hirwaun ironworks and placed them under independent management.

[9] The iron industry had a relatively small impact upon the economy of Aberdare and in 1831 only 1.2% of the population was employed in manufacturing, as opposed to 19.8% in neighbouring Merthyr Tydfil.

[26] In 1836, this activity led to the exploitation of the "Four-foot Seam" of high-calorific value steam coal began, and pits were sunk in rapid succession.

In 1851, the Admiralty decided to use Welsh steam coal in ships of the Royal Navy, and this decision boosted the reputation of Aberdare's product and launched a huge international export market.

The dispute was initiated by the depression in trade which followed the Crimean War and saw the local coal owners successfully impose a reduction in wages.

[32] In common with the rest of the South Wales coalfield, Aberdare's coal industry commenced a long decline after World War I, and the last two deep mines still in operation in the 1960s were the small Aberaman and Fforchaman collieries, which closed in 1962 and 1965 respectively.

[10] As a small village in the upland valleys of Glamorgan, Aberdare did not play any significant part in political life until its development as an industrial settlement.

It was part of the lordship of Miskin, and the ancient office of High Constable continued in ceremonial form until relatively recent times.

Following the granting of a second parliamentary seat to the borough of Merthyr Tydfil in 1867, the Liberals of Aberdare sought to ensure that a candidate from their part of the constituency was returned alongside the sitting member, Henry Austen Bruce.

In 1900, however, Thomas was joined by Keir Hardie, the ILP candidate, who became the first labour representative to be returned for a Welsh constituency independent of the Liberal Party.

During the early decades of the 19th century the ironmasters gradually imposed their influence over local affairs, and this remained the case following the formation of the Merthyr Board of Guardians in 1836.

[45][46] Aberdare, during its boom years, was considered a centre of Welsh culture: it hosted the first National Eisteddfod in 1861, with which David Williams (Alaw Goch) was closely associated.

From the mid 19th century, Aberdare was an important publishing centre where a large number of books and journals were produced, the majority of which were in the Welsh language.

[10][47] With the development of Aberdare as an industrial centre in the nineteenth century it became increasingly apparent that the ancient church was far too small to service the perceived spiritual needs of an urban community, particularly in view of the rapid growth of nonconformity from the 1830s onwards.

St Joseph's has recently undergone much recreational work, almost converting the church into a community centre, surrounded by a beautiful floral garden and leading to the Cwmaman Sculpture Trail.

This can be explained by several factors, including the rise of socialism and the process of linguistic change which saw the younger generation increasingly turn to the English language.

The earliest Welsh Independent, or Congregationalist chapel in the Aberdare area was Ebenezer, Trecynon, although meetings had been held from the late 18th century in dwelling houses in the locality, for example at Hirwaun.

The Independent ministers of nineteenth-century Aberdare included some powerful personalities, but none had the kind of wider social authority which Thomas Price enjoyed amongst the Baptists.

The chapels came together for regular gatherings, including baptismal services which were held in the River Cynon[59] As a result, Price exerted an influence in the religious life of the locality which was far greater than that of any other minister.

The Methodists were numerically powerful and while some of their ministers such as William James of Bethania served on the Aberdare School Board and other public bodies, their constitution militated against the sort of active political action which came more naturally to the Baptists and Independents.

Largely as a result of these criticisms, the main nonconformist denominations worked together to establish a British School, known locally as Ysgol y Comin, which was opened in 1848, accommodating 200 pupils.

Funds were raised which largely cleared the debts and the opening of the school was marked by a public meeting addressed by Price and David Williams (Alaw Goch).

[67] In common with other public bodies at the time (see 'Local Government' above), membership of the School Board was dominated by coal owners and colliery officials, nonconformist ministers, professional men and tradesmen.

Aberdare was noted as "very remarkable" for its traditions of Taplasau Hâf (summer games/dances), races and gwrolgampau ("manly sports") which were said to have been a feature of the area since at least the 1640s.

[73] The potential for crowd support was again demonstrated on 10 November 1908, when the Ynys hosted its second international side as 5,000 spectators watched Aberdare take on the first touring Australian team.