The term is distantly related to the verb march, both ultimately derived from Proto-Indo-European *mereg-, "edge" or "boundary".

After the decline and fall of the Roman Empire which occupied southern Britain until about AD 410, the area which is now Wales comprised a number of separate Romano-British kingdoms, including Powys in the east.

[3] Campaigns and raids from Powys led, possibly around about AD 820, to the building of Wat's Dyke, a boundary earthwork extending from the Severn valley near Oswestry to the Dee estuary.

The March, or Marchia Wallie, was to a greater or lesser extent independent of both the English monarchy and the Principality of Wales or Pura Wallia, which remained based in Gwynedd in the north west of the country.

By about AD 1100 the March covered the areas which would later become Monmouthshire and much of Flintshire, Montgomeryshire, Radnorshire, Brecknockshire, Glamorgan, Carmarthenshire and Pembrokeshire.

[4][9][10] During the period, the Marches were a frontier society in every sense, and a stamp was set on the region that lasted into the time of the Industrial Revolution.

Hundreds of small castles were built in the border area in the 12th and 13th centuries, predominantly by Norman lords as assertions of power as well as defences against Welsh raiders and rebels.

Many new towns were established, some such as Chepstow, Monmouth, Ludlow and Newtown becoming successful trading centres, and these tended also to be a focus of English settlement.

At the top of a culturally diverse, intensely feudalised and local society, the Marcher barons combined the authority of feudal lord and vassal of the King among their Normans, and of supplanting the traditional tywysog among their conquered Welsh.

[citation needed] Under the Laws in Wales Acts 1535–1542 introduced under Henry VIII, the jurisdiction of the marcher lords was abolished in 1536.

The powers of the marcher lordships were abolished, and their areas were organised into the new Welsh counties of Denbighshire, Montgomeryshire, Radnorshire, Brecknockshire, Monmouthshire, and Carmarthenshire.

[citation needed] List of Marcher lordships and successor shires:[8] There is no modern legal or official definition of the extent of the Welsh Marches.

The Marches Way is a long distance footpath which connects Chester in the north of England, via Whitchurch, Shrewsbury, Leominster and Abergavenny to the Welsh capital, Cardiff.