In general, iron ore was mined and smelted even before Roman times, but it was not then a major industry.
Reference has already been made in IN ANCIENT TIMES to the Iron Foundry that existed at Llancaiach as early as 1478, however, between 1750 and 1850 iron was the most important industry in the area and developed in the vicinity of Dowlais, Rhymney and Pontlottyn.
Prior to this period, iron working was mainly concentrated in the Midlands, and in the great woodland area of the Weald of Kent.
A Mr. Lewis of the Van at Caerphilly had started a small ironworks at Dowlais in connection with his Caerphilly ironworks. Massive iron materials for furnaces were brought over the hills of Gelligaer Common by trains of mules. He was soon joined in his enterprise by John Guest who, with a servant, traveled from Broseley, in Worcestershire, sharing a horse. In this fashion, sometimes walking, sometimes resting, to save the horse, he came through the Fochriw area in 1760.
Lewis was a pioneer of the bulk manufacture of iron from pit coal. This required bringing up a new foundry cylinder from Cardiff to Dowlais. Those inhabitants who had earlier witnessed the spectacle of his team of mules conveying material from Caerphilly were now to see a remarkable tableau of a small army of men and twenty-four oxen heaving and battling their way over the old Roman road over Mynydd Fochriw to Twyn-y-Waun and down to their destination.
The finished product of pig iron was transported by the same packhorses over the same route back to Caerphilly and onto Cardiff for onward transmission to ironmongers and agents in London.
The History of the Dowlais Iron Works 1759 - 1970 by John A Owen shows a map of Furnace Leases of 1763 on Alice, Lady Viscountess Dowager Windsor land and depicts the road to "Fochriw and towards Gelligaer" passing from what was to become Dowlais Top through "The Fair Place" that is Twyn-y-Waun which sat on the cross roads of the road to Waun and Merthyr. This map also shows a line drawn around the northern outcrops which depicts the "Direction of the coal and iron ore veins" and this line goes straight through Pant-y-Waun
From the inception of the mass iron workings at Merthyr Tydfil and Dowlais, the iron was conveyed to the port of Cardiff by the Glamorganshire Canal which was constructed in the latter part of the 18th century, reaching Merthyr in 1794.
In 1839 Dowlais had 17 furnaces whilst Penydarren at Merthyr had only 6. It also had a tramway to the Glamorganshire canal before the famous Penydarren Railroad was built.