The Celtic conquest of Wales occurred only a few centuries before the Roman conquest of Britain in AD. 70. The Romans withdrew in A.D. 383. This was followed by the arrival of Christian missionaries from Ireland and the Anglo-Saxon invasions from the east. After the seventh century the Welsh were increasingly isolated from the rest of Europe by the expanding Saxon kingdoms. From this time until the arrival of the Normans, Welsh history can be characterized as a complex pattern of internal disputes between its small kingdoms, shifting alliances between different factions, and a constant series of petty wars between these groups and the Saxon Kingdoms. During the ninth and tenth centuries, there was some success at unification, the establishment of a code of laws along with increasing Saxon legal and cultural influences. Between 1066 and the early twelfth century, Norman colonies, towns, and forts along the east and south further isolated the Welsh. In 1282 the Anglo-Norman conquest of Wales was completed, and between 1400 and 1410 the last Welsh revolt was suppressed. Finally in 1536 the Act of Union occurred whereby Wales was made a principality of England, English became the official language, and English law became dominant.
From about 1750 to 1900 much of Welsh life was greatly changed by the industrial revolution and the Methodist-Calvinist religious revivals. The development of coal and iron mining and smelting in the south resulted in massive movements of Welsh workers to the south. Large numbers of English workers also arrived. This division between the urban-industrial south and the rural-agrarian center and north still remains. The Wesleyan and nonconformist Religious movements stimulated a shift away from the established church and provided a new core of Welsh ethnic consciousness.