Where did the Celts come from

"The peoples known as the Celts are thought to have originated in central Europe, to the east of the Rhine in the areas now part of southern Germany, Austria, Slovakia, the Czech Republic, and Hungary. From around 3,400 years ago, these proto-Celtic peoples expanded across the Continent, and eventually inhabited a large portion of central, western, and northwestern Europe. During the Classical periods of Greece and Rome, Celtic culture was predominiant to the north of the Alps. Even today, Scotland, Wales, Ireland, Cornwall, Cumbria and Brittany are basically Celtic in character. Despite the changes that time has brought, the influence of Celtic traditionis still fundamental."From "The Sacred World of the Celts" by Nigel Pennick

Other authors have stated the Celts may have crossed to Ireland from Portugal/Spain. Common to Celtic music is a form of bagpipe. The Scots use the large mouth blown bagpipes whereas the Irish use a small pipes that use a small bellows to provide the air that operates the pipes. Bagpipes have been documented in Wales since the 12th century. With the general decline of Welsh traditional music in the 19th century, the pipes disappeared from use by the late 19th century. There are no definite surviving examples of bagpipes that were used in Wales, but there are drawings and carvings that show a style of bagpipe very similar to those used in Brittany and Galicia, otherwise known as the Atlantic Bagpipe. There is also a description from Anglesey of what seems to be a bagpipe played by herdsmen, with a cowhorn attached to the chanter, probably a pibgorn with a bag attached. In the last 20 or so years there has been a revival of piping in Wales. A repertoire of Welsh piping tunes has been rediscovered and developed, along with the instruments, based on pipes from Brittany and Galicia, as well as using pipes from these regions.