Mac Fhirbhisigh
Mac Fhirbhisigh, also rendered MacFirbis or Forbes, was the surname of an Irish hereditary family of historians, genealogists, poets and legal scholars.
Last updated August 26, 2026
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Overview
Mac Fhirbhisigh, commonly anglicised as MacFirbis and sometimes associated with the name Forbes, identifies an Irish hereditary learned family rather than a modern commercial brand. The family was based for much of its documented history at Lecan, in Tireragh, County Sligo, although earlier traditions place its origins at Cong. Its members served patrons connected with the Uí Fiachrach Muaidhe, a branch of the wider Uí Fiachrach dynasty of Connacht, and were valued for preserving and transmitting historical, genealogical and literary knowledge. Family tradition traced the line to Dathí, a legendary or semi-historical early king of Connacht, and more immediately to the descendants of Amhailgadh. The family’s inherited professional role appears to have developed from ecclesiastical or estate-based service into work as historians and genealogists. Members may also have acted as poets, brehons, and possibly musicians, reflecting the broad responsibilities of medieval Irish learned families. Their work was performed for several aristocratic and dynastic patrons rather than for a commercial market. The family’s recorded members extend from the medieval period into the seventeenth century. Amhlaoibh Mór mac Fir Bhisigh is recorded as having died in 1138, while Domhnall na Sgoile Mac Firbhisigh was active around the middle of the thirteenth century and Gilla Isa Mac Fir Bisigh died in 1301. Giolla Íosa Mór Mac Fhirbhisigh, active approximately from 1390 to 1418, was among the better-known late-medieval members. After establishing themselves at Lecan, the family built Lacken Castle, also known as Castle Forbes, in 1560. The castle became associated with a school of poetry and history maintained by the family. It is now ruined, and the family had lost possession of it by 1625. Fear Dorcha MacFhirbhisigh, associated with the period around 1600, was noted for travelling in Scotland, illustrating the geographical reach of the family’s scholarly activity. The most prominent surviving figure is Dubhaltach Mac Fhirbhisigh, active in the seventeenth century and deceased in January 1671. He compiled Leabhar na nGenealach, a large collection of Irish genealogical material and one of the most important surviving works associated with the native Irish learned tradition. The family is therefore chiefly remembered for its contribution to Irish historiography, genealogy and the preservation of dynastic and regional knowledge. There is no evidence in the supplied sources that Mac Fhirbhisigh operates as a contemporary consumer brand, company or commercial product line.
History
The Mac Fhirbhisigh family, also known as MacFirbis and associated in anglicised form with Forbes, belonged to the hereditary learned classes of Gaelic Ireland. Its members were chiefly historians and genealogists, though the family’s service may also have included poetry, legal expertise as brehons and possibly music. Their work supported dynastic households by recording ancestry, history, customary law and the legitimacy of aristocratic lineages. Traditions connected the family with Dathí, described as one of the last pagan kings of Connacht, and with the Uí Fiachrach dynasty. The more immediate ancestral line was said to descend from Amhailgadh, whose brothers were associated with the O'Dowd and O'Shaughnessy families. These genealogical claims reflect the political and cultural importance of ancestry in medieval Connacht, although individual elements of the traditional pedigree should be understood as part of the historical record preserved by the learned families rather than as independently verified modern biography. The family was initially associated with Cong. It may have held an erenagh role before becoming identified more directly with historical and genealogical scholarship for the Uí Fiachrach Muaidhe and other patrons. Early recorded members include Amhlaoibh Mór mac Fir Bhisigh, who died in 1138, Domhnall na Sgoile Mac Firbhisigh, active around 1250, and Gilla Isa Mac Fir Bisigh, who died in 1301. Giolla Íosa Mór Mac Fhirbhisigh, active from roughly 1390 to 1418, represents a notable figure from the late-medieval phase of the family’s history. The family later became strongly associated with Lecan, or Lacken, in Tireragh, County Sligo. In 1560 it constructed Lacken Castle, also called Castle Forbes, in Kilglass parish. The site functioned as a centre for the family’s learned activities, including a school of poetry and history. The Mac Fhirbhisighs no longer possessed the castle by 1625, and the building is now ruined. The family’s scholarly network was not confined to its immediate locality: Fear Dorcha MacFhirbhisigh, active around 1600, was remembered as having travelled in Scotland while pursuing his learned profession. Dubhaltach Mac Fhirbhisigh was the family’s most celebrated surviving scholar. Active in the seventeenth century and deceased in January 1671, he assembled Leabhar na nGenealach, a substantial compilation of Irish genealogies. His work preserved information concerning the origins, relationships and status of numerous Irish families and remains an important source for the study of medieval and early modern Gaelic society. The family’s historical significance consequently lies in its role as a transmitter and organiser of inherited knowledge, not in commercial production or corporate activity. The subject described by the authoritative Wikipedia entry is therefore a historical Irish family name and learned tradition. It should not be treated as a modern brand, operating business or corporate entity without additional evidence.
- 1671
Death of Dubhaltach Mac Fhirbhisigh
[1]Dubhaltach Mac Fhirbhisigh died in January 1671 after compiling major genealogical material, including Leabhar na nGenealach.
- 1640
Dubhaltach Mac Fhirbhisigh’s scholarly period
[1]Dubhaltach Mac Fhirbhisigh was active as a genealogist and compiler during the seventeenth century, approximately from the 1640s until his death.
- 1625
Loss of the family castle
[1]The Mac Fhirbhisigh family had lost possession of Lacken Castle by this date.
- 1560
Construction of Lacken Castle
[1]The family built Lacken Castle, also known as Castle Forbes, at Lecan in County Sligo. The site became associated with a school of poetry and history.
Death of Amhlaoibh Mór mac Fir Bhisigh
[1]Amhlaoibh Mór mac Fir Bhisigh is recorded among the earliest known members of the family and is said to have died in 1138.
Domhnall na Sgoile Mac Firbhisigh active
[1]Domhnall na Sgoile Mac Firbhisigh is recorded as active around the middle of the thirteenth century.
Death of Gilla Isa Mac Fir Bisigh
[1]Gilla Isa Mac Fir Bisigh, one of the early documented family members, died in 1301.
Giolla Íosa Mór Mac Fhirbhisigh active
[1]Giolla Íosa Mór Mac Fhirbhisigh was active approximately from 1390 to 1418 and is noted as a prominent late-medieval member.
Products and positioning
A hereditary Irish learned family associated with historiography, genealogy, poetry and legal learning, rather than a contemporary commercial brand.
Genealogical manuscript
Leabhar na nGenealach
A large compilation of Irish genealogies produced by Dubhaltach Mac Fhirbhisigh in the seventeenth century. The work gathered lineage and ancestry information concerning Irish families and is the principal surviving scholarly achievement associated with the Mac Fhirbhisigh name.
Sources3 sources
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