Penywern was a typical  industrial village built for the workers of the Ivor Works in 1839. Here was the permanent barracks for the Volunteers. After the Merthyr Rising of 1831 soldiers were permanently barracked at Penywern to keep an eye on the growing town of Merthyr Tydfil. On the tithe schedule of 1850 the owner of the land here was the Dowlais Iron Company. At first all there was in Penywern were the Barracks, as is shown on the 1850 tithe map, however by the 1875 ordinance survey map Penywern had developed and Lower Row and Upper Row are shown. The reservoirs and ponds which once fed water into the Dowlais Works are situated in this area. These are now of great historical significance, especially as so little now remains of the great Dowlais Works.  There are 2 large and 2 small ponds east of Penywern and also a reservoir to the south. This was a self-sufficient community and there were a number of shops here. Late nineteenth century directories show that Morgan Evans was a baker, grocer, tea dealer at number 4 Penywern. The working men of the area were mainly employed in coal mining. The community built their community church vestry during the General Strike of 1926, when so many skilled men were force to be idle due to the national economic climate.

The famous historian Gwyn Alf Williams was born in Lower Row in a cottage belonging to his grandmother, Mrs Morgan. In 2005 the Dic Penderyn Society and the Merthyr Tydfil Heritage Trust erected a plaque on the walls of this property in commemoration of the birth of Gwyn Alf  .There was quite a large Spanish community here before the First World War. The Spaniards who settled here from 1900 onwards built Alphonso Street and King Carlos Street. The exposed height of this area means that it is very vulnerable when there are any falls of snow.  During the severe winter of 1947 a train at Penywern became snowbound for several days. This village has undergone many changes in recent years; the Tre-ivor Arms public house, now closed was once called the Ivor Arms. Penywern Chapel, was an Independent Chapel, but it was demolished in the late 1990s, and today modern houses are on its former site.