Glamorgan (/ɡləˈmɔːrɡən/), or sometimes Glamorganshire (Welsh: Morgannwg [mɔrˈɡanʊɡ] or Sir Forgannwg [ˈsiːr vɔrˈɡanʊɡ]), was one of the thirteen counties of Wales that existed from 1536 until their abolition in 1974. It is located in South Wales. Originally an early medieval petty kingdom of varying boundaries known in Welsh as Morgannwg (or Glywysing), which was then invaded and taken over by the Normans as the Lordship of Glamorgan. The area that became known as Glamorgan was both a rural, pastoral area, and a conflict point between the Norman lords and the Welsh princes. It was defined by a large concentration of castles.
After falling under English rule in the 16th century, Glamorgan became a more stable county, and exploited its natural resources to become an important part of the Industrial Revolution. Glamorgan was the most populous and industrialised county in Wales, and was once called the "crucible of the Industrial Revolution", as it contained the world centres of three metallurgical industries (iron, steel and copper) and its rich resources of coal.