Welsh historians begin their history dated 447 A.D. In the earliest recognized accounts, the "Annales Cambriae", it states:
"447 Days as dark as night". [see earlybritishkingodms.com/sources/annales.html]
Dark as night, an interesting beginning to a nation.
It was at this beginning that the tribal groups had made their claims to the land, and had begun their settlement patterns. In their hills and mountains, a branch of the Celtic tongue evolved seeming to concentrate on the bilabial consonants p, b, t, and hard palate sounds k. (the Welsh c) This "Brythonic" branch became the Welsh, Cornish, and Breton. Thus Welsh must have been fairly well developed before the emigration to Brittany, from Wales, where the Brythonic tongue took root. Welsh was spoken centuries before it became a written language. [Following the Celtic tradition of oral transmission of history, legends, and family stories.]
To add to the complexity of the language, the Celtic languages had developed a process called "mutation". This was a change of an initial consonant, depending on the character of the preceding word. Thus, depending on the preceding word, the initial consonants of the word that follows will sometimes change. Knowledge of these sound changes [mutations] became important for anyone wishing to understand the sounds and pronunciation of the Welsh. [This was particularly a problem for the English ear recording their sounds in future documents.]
The following is a list of the mutations which need to be recognized:
mutation of B = F and M
mutation of F = B and M
mutation of M= F
mutation of P = B, Mh, and Ph
mutation of T = D, Nh, and Th
L at the beginning of a word always signifies a mutation.
Wow! There you have it. For a discussion of the Welsh language see: