An official language

The Welsh legal system was largely conducted in Welsh, and the great prose work the Mabinogi was written.

The construction of Offa's Dyke in the late eighth century was a turning point in Britain's history. It effectively marked out a boundary between the Britons of the west (now Wales) and Germanic tribes of the east (now England) - although there still remained Welsh speakers living to the east of the boundary and English speakers to the west.

Wales, given a geographic expression by the Dyke, was to enjoy a cultural and political autonomy that lasted until the Norman invasions. The word Cymry had been used as early as the seventh century, but it now became popular to describe the Welsh. Derived from the Brittonic word Combrogi, meaning fellow countryman, it is also the origin of the place name Cumbria.

As the Welsh kingdoms developed behind the Dyke, the Welsh language began to assume official status. Whereas previously Latin was the main language of writing, early in the ninth century its alphabet was adapted for the writing of Welsh.

A memorial in Tywyn dated to 810 AD carries an inscription in Early Welsh, barely understandable to a modern Welsh speaker: "Cingen celen tricet nitanam" translates as "The body of Cingen dwells beneath". And glosses in Welsh - that is, written notes in margins - have been found on ninth and 10th century medieval manuscript.

The ninth century king Hywel Dda (Hywel the Good) was one of the more powerful Welsh rulers of the period. As well as temporarily uniting the country, he is also credited with the codification of the law of Wales.

Of the law books that survive dating from the 13th century, some are in Latin but the majority are written in Welsh. Hywel Dda's reforms made Wales one of the first countries of medieval Europe to have codified laws in its own language, and scholars state that the oral language of law was also Welsh.

The years preceding the Norman invasions of 1067 were generally peaceful. Academics believe this enabled the writing of the famous group of legends popularly known as the Mabinogion, or more correctly Mabinogi, in around 1050 AD.

Though the original manuscript is long lost, the tales are preserved in two 14th century manuscripts: the White Book of Rhydderch which is kept in the National Library of Wales at Aberystwyth and the Red Book of Hergest, now in the Bodleian Library at Oxford.

This prose masterpiece was probably the work of one author working in a Celtic monastery. Professor Gwyn Jones calls them "Wales' own distinctive contribution to medieval prose literature".