Cornish is one of the family of Celtic languages, closely related to Welsh and Breton and slightly more distantly to Irish, Scots Gaelic and Manx. In the first millennium BC the British language, which was the predominant language of the islands, split in two, forming the base for the modern Gaelic celtic languages of Scotland, Ireland and Man in the north, and the modern Brythonic celtic languages of Wales, Cornwall and Brittany in the south.
Cornish was spoken throughout Cornwall and west Devon up as far as Exeter until the Saxon king Athelstan defeated Hywel, the last independent king of Cornwall, in 936 AD. Athelstan drove the Cornish out of Exeter and declared the river Tamar to be the border of his kingdom, and this border is, of course, still current today.
The period from 1200 to 1600 is known as Middle Cornish, and during this time numerous religious plays were written by the canons at Glasney College. They were performed in open air rounds known as plen-an-gwary, as can be found still in many locations around Cornwall, the best examples being St Just in Penwith and Perran Round near Perranporth. Of the surviving plays, the largest is a trilogy dating from the mid fourteenth century called the Ordinalia, which comprises the Origin of the World, the Passion of Christ and the Resurrection of Our Lord.
During the next two centuries, Cornish developed into the phase known as Late Cornish. A group of bilingual scholars in the Penzance area gathered together to try to preserve their language. Secular prose appears in this period too, and perhaps the most famous Cornish language folk tale, Jowan Chy an Hor, was written circa 1667 by Nicholas Boson of Newlyn. The final written piece of Cornish before the revival is a letter by William Bodinar, who learnt Cornish at sea from older fishermen. The date of this letter is 1776.
By the nineteenth century, Cornish had died as a spoken community language, although there are records of the language being spoken particularly at sea by Newlyn fishermen. In 1904 Henry Jenner published his Handbook of the Cornish language, based on the texts. This started the revival of Cornish as a living, spoken language, and Jenner's work was picked up and continued by Robert Morton Nance, who researched and gathered together more fragments of the language, finally developing a regularised spelling system based on the medieval texts, known as Unified Cornish. The revival continued to grow throughout the twentieth century, with evening classes, events and examinations being established. Cornish today is a living language and is recognised as such under the European Charter for Regional or Minority Languages. Starting to teach Cornish in schools is a major current activity.
The original KDL course is still available. It uses the spelling system known as Common Cornish (Kernewek Kemmyn - KK). There are other forms, all mutually intelligible. It was decided that, in order to progress the language to its fullest potential, there should be a standard spelling system for use in public life and schools. This form is known as the Standard Written Form (Furv Skrifys Savonek - FSS) and it is expected that this spelling system will become more widely used in the future. The new KDL Course is available in both the Standard Written Form and Common Cornish. The two forms are very similar.