This type of harp has always been known by the feminine term cruit but by 1204 was certainly known by the masculine term 'clàr' (board) and, by the 14th century, by the feminine form of 'clàr', i.e., 'clàirseach/clàrsach'. (Gd.)
The origins of the Gaelic triangular harp go back at least to the first millennium. There are several stone carvings of triangular harps from the 10th century, many of which have simple triangular shapes, generally with straight pillars, straight string arms or necks, and soundboxes. There is stone carving evidence that the lyre or non-triangular harp were present in Ireland during the first millennium Evidence for the triangular harp in Pictish Scotland dates from the 9th century.
The clàrsach or harp was the most popular musical instrument in later medieval Scotland and Ireland and Gaelic poets portrayed their Pictish counterparts as very much like themselves.
Scotland, because of her affinity and intercourse [with Ireland], tries to imitate Ireland in music and strives in emulation. Ireland uses and delights in two instruments only, the harp namely, and the tympanum. Scotland uses three, the harp, the tympanum and the crowd. In the opinion, however, of many, Scotland has by now not only caught up on Ireland, her instructor, but already far outdistances her and excels her in musical skill. Therefore, [Irish] people now look to that country as the fountain of the art.
The clàrsach played by the Gaels of Scotland and Ireland between the 11th and 19th centuries was certainly wire-strung. The Irish Maedoc book shrine dates from the 11th century, and clearly shows a harper with a triangular framed harp including a "T-Section" in the pillar. The Irish word lamhchrann or Scottish Gaelic làmh-chrann came into use at an unknown date to indicate this pillar which would have supplied the bracing to withstand the tension of a wire-strung harp.
The Irish and Highland Harps by Robert Bruce Armstrong describes these ancient harps. There is historical evidence that the types of wire used in these harps are iron, brass, silver, and gold. Three pre-16th-century examples survive today; the Brian Boru Harp in Trinity College, Dublin, and the Queen Mary and Lamont Harps, both in Scotland.
One of the largest and most complete collections of 17th-century harp music is the work of Turlough O'Carolan, a blind, itinerant Irish harper and composer. At least 220 of his compositions survive to this day.
Since the 1970s, the tradition has been revived. Alan Stivell's Renaissance de la Harpe Celtique (perhaps the best-seller harp album in the world), using mainly the bronze strung harp, and his tours, have brought the instrument into the ears and the love of many people. Ann Heymann has revived the ancient tradition and technique by playing the instrument as well as studying Bunting's original manuscripts in the library of Queens University, Belfast. Katie Targett-Adams (KT-A) is currently leading the modern day crossover movement for the clarsach, performing to mainstream audiences across the globe, notably China. Other high profile players include Patrick Ball, Cynthia Cathcart, Alison Kinnaird, Bill Taylor, Siobhán Armstrong and others.
As performers have become interested in the instrument, harp makers ("luthiers") such as Jay Witcher, David Kortier, Ardival Harps, Joël Herrou and others have begun building wire-strung harps. The traditional wire materials are used, however iron has been replaced by steel and the modern phosphor bronze has been added to the list. The phosphor bronze and brass are most commonly used. Steel tends to be very abrasive to the nails. Silver and gold are used to get high density materials into the bass courses of high quality clàrsachs to greatly improve their tone quality. In the period, no sharping devices were used. Harpers had to re-tune strings to change keys. This practice is reflected by most of the modern luthiers, yet some allow provisions for either levers or blades.
Seán Ó Riada used the harpischord for his interpretations of the Irish harper Turlough O'Carolan during Riada's work with the band Ceoltori Cualann (later to become The Chieftans). Riada used harpsichord for the latter with the justification that the harpsichord best replicated the sound of the metal strings of the early Irish harp, in comparison with other available instruments.
- Karen Ralls (2000). Music and the Celtic Otherworld: From Ireland to Iona. Polygon at Edinburgh. ISBN 978-1-902930-09-1.
- "The Origins of the Clairsach or Irish Harp", Musical Times, Vol. 53, No 828 (Feb 1912), pp 89–92.
- Forsyth, K.; J.T. Koch (2000). "Forsyth: Evidence of a lost Pictish source in the Historia Regum of Symeon of Durham". Kings, Clerics and Chronicles in Scotland, 500-1297: Essays in Honour of Marjorie Ogilvie Anderson on the Occasion of Her Ninetieth Birthday. Four Courts Press. pp. 27–28. ISBN 978-1-85182-516-5.
- Gerald of Wales, "Topographia Hibernica", 94; tr. John O' Meary, The History and Topography of Ireland, (London, 1982).
- JT Koch (ed). Celtic Culture. A Historical Encyclopaedia ABC-CLIO 2006 pp 1627–1628
- David Cooper; Kevin Dawe (1 January 2005). The Mediterranean in Music: Critical Perspectives, Common Concerns, Cultural Differences. Scarecrow Press. pp. 220–. ISBN 978-0-8108-5407-9.
- Timothy Mason Love (2009). The Film Music of Sean O Riada. ProQuest. pp. 66–. ISBN 978-1-109-20305-9.