The name itself comes from outside. In Old English, the word wealas meant any inhabitant of the old Western Roman Empire - the Romanised Britons who had lived under Rome and who, when the Saxons arrived in the 5th and 6th centuries, were pushed steadily westward into the corners of the island where the new settlers had not yet reached. Wales got the name. So did Cornwall - whose second syllable preserves the same root - because before the Saxons reached Devon and pushed the Britons further still, the Cornish kingdom was West Wales to the eye of an Anglo-Saxon chronicler. The label moved as the Saxons did. By the late Middle Ages, the modern Wales had it for keeps, and West Wales had narrowed to mean the part that lay furthest west of all.

The most enduring definition of West Wales covers Pembrokeshire, Ceredigion and Carmarthenshire - the three counties that historically made up the principality of Deheubarth, ruled from Dinefwr in the 9th and 10th centuries by the Welsh princes whose names crowd into the older histories: Hywel Dda the law-giver, Rhys ap Tewdwr, the Lord Rhys. This is the West Wales of the West Wales Regional Partnership Board, and the area covered today by Hywel Dda University Health Board - the NHS region that takes its name from the king who codified Welsh law in the 940s. From 1974 to 1996 the same three counties formed the preserved county of Dyfed, governed as one administrative unit before being broken apart again into three. The boundaries keep being redrawn. The land beneath stays the same.

From above, this part of Wales is unmistakable - a great curving peninsula of green farmland and dark hill country, with the long Atlantic-fronted coastline of Pembrokeshire on the west, the soft Ceredigion arc of Cardigan Bay on the north, and the broad estuary of the Carmarthen Bay on the south. Rivers fall through Mid Wales out into Cardigan Bay: the Teifi, the Aeron, the Ystwyth. The Cambrian Mountains rise inland. The coast is fringed with seaside towns and pilgrimage churches and the rougher remains of medieval Norman castles - Cardigan, Cilgerran, Carmarthen, Pembroke itself. The whole region is sparsely populated; the largest town, Carmarthen, has fewer than 16,000 people. Most of the settlements you fly over are villages of slate-roofed cottages clinging to small ports and river valleys.

West Wales is reachable, just barely, by train. The West Wales Line runs out of Swansea through Carmarthen and divides - one branch heading south-west to Pembroke Dock, another west to Milford Haven, a third northwest to Fishguard for the ferry to Ireland. The Heart of Wales Line crosses the region from south to north on its slow rural journey from Swansea up through Llandrindod Wells. The Cambrian Coast Line hugs the northern shore of Cardigan Bay from Aberystwyth around to Pwllheli - one of the most scenic rail journeys in Britain, passing within sight of Snowdonia. Heritage steam survives at the Gwili, Teifi Valley and Vale of Rheidol railways. By road, the A40 runs west from London through Carmarthen to Haverfordwest; the A487 follows the coast. The journey takes time. Time is part of what people come here for.