Welsh tradition stretches back into prehistory (see Celt; Great Britain). In the first centuries A.D., Celtic-speaking clans of shepherds, farmers, and forest dwellers defended their homes against Roman invaders, who penetrated the north to found Segontium (near Caernarvon) and the south to found Maridunum (now Carmarthen). But the Roman effect upon Wales was light, and Welsh clans continued to dominate large areas of Great Britain, north to the Clyde and the Firth of Forth and south past the Bristol Channel into present Somerset, Devonshire, and Cornwall. They were converted to Christianity by Celtic monks, notably St. David. Although the Anglo-Saxon conquest of E Britain (late 5th cent.) did not seriously affect the Welsh, the invaders did thrust between the main body of Welsh and those south of the Bristol Channel (who nevertheless maintained their national identity for centuries).
Border wars were chronic between the Welsh and the seven English kingdoms known as the heptarchy. The sturdy Welsh fighters, who took the name Cymry [compatriots], withstood the forces of the kings of Mercia and Wessex and later the harrying of the Norsemen. The disparate clans of pastoral people gradually coalesced. Hywel Dda, king of Wales in the mid-10th cent., collected Welsh law and custom into a unified code. At the same time the position of the bard, which was later to yield a wealth of poetry, music, and learning, was formalized. Defense of the besieged hills went on, and Gruffydd ap Llywelyn, the ruler of Wales, maintained Welsh independence until his death in 1063.
William I of England tried to deal with the Welsh by setting up border earldoms to protect his newly won kingdom from their incursions. The power of the border earls (see Welsh Marches) grew steadily, and Wales was increasingly threatened with English conquest, although Welsh foot soldiers, moving swiftly and secretly over the mountain paths, resisted through 200 years of guerrilla warfare. When the English made inroads in the north, Rhys ap Tewdr held sway in the south, and only after his death (1093) did the Anglo-Norman barons take full possession of the Vale of Glamorgan. Dissension within England in the early 12th cent. relaxed pressure on the Welsh princes, and medieval Welsh culture approached its full blossom (see eisteddfod; Mabinogion).
Nevertheless, although invasions from England were repeatedly thwarted and although Llywelyn ap Iorwerth (d. 1240) united the Welsh and gained power by skillfully intervening in the troubled English affairs of King John, the end was certain. During the reign of Llywelyn's grandson, Llywelyn ap Gruffydd, English conquest of Wales was finally accomplished by Edward I in 1282. The Statute of Rhuddlan (1284) established English rule. To placate Welsh sentiment, Edward had his son (later Edward II), who had been born at Caernarvon Castle, made prince of Wales in 1301; thus originated the English custom of entitling the king's eldest son prince of Wales.
Changes in Welsh life, although few, included a gradual cultural decline and the growth of market towns through trade with England. Wool became a staple source of revenue. The Norman barons were left undisturbed in their marcher lordships. Early in the 15th cent. Owen Glendower led a revolt that had a brief but amazing success, and Welsh leaders continued to seek advantage from disturbances in the domestic affairs of their conquerors. Henry VII, the first Tudor king, who ascended the English throne in 1485, was the grandson of Owen Tudor, a Welshman. Tudor policy toward Wales was one of assimilation on a basis of equality. Welsh lands, including the marches, were converted into shires, and primogeniture replaced the old Welsh system of tenure (see gavelkind).
Leading Welsh families held their lands from the king; the others became leaseholders and tenants after the English pattern. The feudal aristocracy became versed in English manners and were received at the English court. Thus a deep breach, fostered by economic inequality, opened between landlord and tenant and remained unhealed for centuries. A judicial council of Wales, dating from the 15th cent., enhanced royal authority. The Act of Union (1536) and supplementary legislation completed the process of administrative assimilation by abolishing all Welsh customary law at variance with the English and by establishing English as the language of all legal proceedings. Welsh representatives entered the English Parliament; from 1536 onward, the separate history of Wales was mainly religious and cultural.
The Reformation came belatedly to Wales. Catholic tradition died slowly under Elizabeth I and James I; Puritanism was stoutly resisted, and the Welsh supported Charles I in the English civil war. Oliver Cromwell had to use oppressive measures to get the Welsh to adopt Puritan practices. In the 18th cent. Wales turned rapidly from the Established Church to dissent with strong Calvinist leanings. This was accompanied by great advances in the field of popular education, which attained unusually high standards. Welsh evangelicism had links with the English movement but was actually a native development. The Calvinistic Methodist Church gathered in great numbers of Welsh from the Church of England and bolstered Welsh nationalism, one of the most successful nonpolitical nationalist movements of the world. The strong hold of evangelical Protestantism on Wales was to make the establishment of the Church of England there the dominant question in Welsh politics in the later 19th cent.; one of the last acts of Parliament that applied to Wales alone was the disestablishment of the church in 1914.
Long before that time the tenor and tempo of Welsh life had been changed by the Industrial Revolution. The mineral wealth of Wales was opened to exploitation, at first in the north, then in the rich coal fields of the south. The accent shifted from the sheep walks and farms to the coal pits and factories. By the early 19th cent. the effects of industrialization threatened both cottage industry and agriculture. The distress of rural Wales was dramatically evidenced in the Rebecca Riots of 1843, when poor farmers destroyed toll booths, and in the emigration of large numbers of Welshmen, many to the United States. Numerous company towns sprang up in S Wales, which by the late 19th cent. was the world's chief coal-exporting region. With the benefits of industrialization, however, came poverty and unemployment, which intensified in the years of economic decline following World War I, particularly in the late 1920s and the 1930s.
Although Welsh interests had spokesmen in the British government in the early 20th cent.—the flamboyant David Lloyd George and the Welsh supporters of the Liberal party—chronic poverty and increasing unemployment continued almost unchecked until World War II. After the wartime industrial boom the Labour government, which drew substantial support from the socialist stronghold of S Wales, undertook a full-scale program of industrial redevelopment. This included reorganization of the coal mines and tinplate manufacture under government control, introduction of diversified industry, and improvement of communications, housing, and technical education. These actions did not save the coal industry; most of the mines in Wales have been closed, and the few remaining ones have been privatized.
As in earlier days, Welsh nationalism has undergone a revival since the mid-20th cent., with a special interest in education and the arts. The modern National Eisteddfod perpetuates interest in Welsh language, poetry, and choral music. Since 1944, primary and secondary schools have been established with Welsh as the sole language of instruction. A Welsh-language television channel opened in 1982, and there are several Welsh arts, opera, and literature councils on the national level (see also Welsh literature).
In 1979, Welsh voters decisively defeated a British proposal for limited home rule, but in 1997 they narrowly passed a referendum to establish a 60-member assembly. Elections were held in 1999, with the Labour party winning the most seats and forming a coalition with the Liberal Democrats. Labour formed a government alone after the 2003 vote, in coalition with the nationalist Plaid Cymru after the 2007 vote, and alone after the 2011 vote.
Parliamentary legislation passed in 2006 and effective in mid-2007 allowed the assembly to enact laws for Wales, subject to approval from the British parliament, in areas in which the assembly has devolved responsibilities. In 2011 voters approved increased legislative powers for the assembly, allowing it to act independently of Parliament in areas for which it is responsible.