Deda mac Sin

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Deda mac Sin (Deda, son of Sen) was a prehistoric king of the Érainn of Ireland, possibly of the 1st century BC. Variant forms or spellings include Ded, Dedu, Dedad, Degad, Dega, Dego, Deguth and Daig, with some of these occurring as genitives although usage is entirely unsystematic, besides the rare occurrence of the obvious genitive Dedaid. He is the eponymous ancestor of the Clanna Dedad,[1][2] and may also have been a King of Munster.

Deda mac Sin
IssueÍar mac Dedad and Dáire mac Dedad,
Conganchnes and Conall Anglonnach
Era dates
1st century BC
HouseClanna Dedad

Through his sons Íar mac Dedad and Dáire mac Dedad, Dedu is an ancestor of many famous figures from legendary Ireland, including his "grandsons" (giving or taking a generation) Cú Roí mac Dáire and Eterscél, "great-grandsons" (again) Conaire Mór and Lugaid mac Con Roí, and more distant descendant Conaire Cóem. A third son was Conganchnes mac Dedad. Through these Dedu is also an ancestor of several historical peoples of both Ireland and Scotland, including the Dál Riata, Dal Fiatach, Múscraige, Corcu Duibne, and Corcu Baiscind, all said to belong to the Érainn (Iverni), of whom the Clanna Dedad appear to have been a principal royal sept.

The generations preceding Dedu mac Sin in the extant pedigrees appear artificial.[3][4] Eventually they lead through Ailill Érann to a descent from Óengus Tuirmech Temrach[5] and thus a distant kinship with the Connachta and Uí Néill, whose own pedigree is in fact unreliable before Túathal Techtmar.

A proto-historical sept of the Clanna Dedad are known as the Dáirine,[6] descending from Dáire mac Dedad and/or Dáire Doimthech (Sírchrechtach), and are later known as the Corcu Loígde. Alternatively this may be used synonymously, with some confusion created by their identification with the Darini of prehistoric Ulster. In any case, the Darini and Iverni are clearly related.[7]

According to the Book of Glendalough (Rawlinson B 502) and Laud 610 pedigrees,[8][9] a brother of Dedu was Eochaid/Echdach mac Sin, from whom descend the Dál Fiatach of Ulster. But alternatively they descend directly from Cú Roí mac Dáire,[10] and thus from the Clanna Dedad proper. The precise relation of the Dál Fiatach to the Ulaid of the Ulster Cycle, rivals of the Clanna Dedad, is lost to history.

Eoin MacNeill finds the Conaille Muirtheimne to also descend from Dedu mac Sin, from another son Conall Anglonnach,[11] believing they are quite mistakenly thought to be Cruthin, as found in later genealogies.

Dui Dallta Dedad was a foster-son of Dedu.

There is also an Ogham of Dedu (Ogam Dedad) found in the Book of Ogams. Over one third of all Irish ogham inscriptions are found in the lands of his descendants the Corcu Duibne.[12]

The Sil ConairiEdit

The Síl Conairi were those septs of the Clanna Dedad descended from Conaire Mór,[13] namely the Dál Riata, Múscraige, Corcu Duibne, and Corcu Baiscinn.[14] The first, presumably settling in far northeastern Ulster in the prehistoric period, would famously go on to found the Kingdom of Scotland. The Royal Family of Scotland, the House of Dunkeld, were described as the "seed of Conaire Mór" as late as the twelfth century.[15] Through the House of Dunkeld and Conaire Mór, Dedu mac Sin is an ancestor of the modern British royal family. The last king in the direct male line from the Clanna Dedad and Sil Conairi was Alexander III of Scotland (d. 19 March 1286).

The remaining Síl Conaire would settle and/or remain in Munster, where, although retaining their distinctive identity, they would be overshadowed first by their Dáirine (Corcu Loígde) kinsmen, and later fall under the sovereignty of the Eóganachta. But it appears the Síl Conaire, and especially the Múscraige, actually acted as prominent facilitators for the latter, and this would presumably have been in opposition to the Dáirine.[16] A late and unexpected king of Munster from the Múscraige was Flaithbertach mac Inmainén (d. 944).[17]

The birth, life, and fall of Conaire Mór are recounted in the epic tale Togail Bruidne Dá Derga.[18] Two distantly related tales of more interest to genealogists are De Síl Chonairi Móir [19] and De Maccaib Conaire.[20] In these he is confused with his descendant Conaire Cóem.

The Dál Fiatach and Cú RoíEdit

The descent of the Dál Fiatach princes of Ulster from Dedu mac Sin is less secure, but nonetheless is supported by independent medieval sources (and contradicted by others).

The Dáirine (Corcu Loígde)Edit

As early as 1849, the great Irish scholar John O'Donovan noted that the pedigree of the Corcu Loígde, the leading historical descendants of the Dáirine, is corrupt for many of the generations preceding the legendary monarch Lugaid Mac Con.[21]

Descent of the Clanna DedadEdit

Skipped generations are given in the notes.


  1. ^ Pokorny 1918
  2. ^ Dobbs 1917
  3. ^ Kelleher 1968
  4. ^ Dobbs 1917, p. 12
  5. ^ Sin m. Rosin m. Trein/Trer m. Rothrein/Rothrer (m. Rogein) m. Arndil/Arndail m. Maine Mór m. Forgo m. Feradach m. Ailill Érann m. Fiachu Fer-mara m. Óengus Tuirmech Temrach
  6. ^ Dobbs 1917, p. 10
  7. ^ for extensive discussion (in German), see Pokorny 1918
  8. ^ ed. Ó Corráin 1997
  9. ^ ed. Meyer 1912
  10. ^ Dobbs 1921, pp. 330–1: ... Iatach Find (a quo Dal Fiatach) m. Fuirme m. Conrui m. Dairi Sirchrechtaig m. Deadad m. Sin m. Rosin...
  11. ^ MacNeill 1911, pp. 97–8
  12. ^ MacNeill 1909, p. 334
  13. ^ Dobbs 1917, p. 9
  14. ^ Byrne, p. 63
  15. ^ Chadwick, p. 121
  16. ^ see Byrne, pp. 45, 181
  17. ^ Byrne, pp. 204, 214
  18. ^ for editions, translations, commentary, and studies, see Togail Bruidne Dá Derga
  19. ^ Lucius Gwynn, "De Sil Chonairi Móir", in Ériu 6 (1912): 130–43.
  20. ^ Lucius Gwynn, "De Maccaib Conaire", in Ériu 6 (1912): 144–53.
  21. ^ O'Donovan, pp. 57, 86
  22. ^ "Old" son of "Very Old"; see Kelleher 1968
  23. ^ Dobbs 1917, p. 18: "Eogan son of Iar son of D... third king of Munster of Clanna D..."
  24. ^ Rawlinson ¶1696: Conaire Cáem (m. Mug Láma) m. Lugdach m. Cairpri Chrommchinn m. Dáire Dornmáir m. Cairpre m. Conaire Móir
  25. ^ Rawlinson ¶1696: Ercc m. Echdach Muinremuir m. Óengusa Fir m. Feideilmid m. Óengusa m. Feideilmid m. Cormaicc m. Croithluithe m. Find Féicce m. Achir m. Echdach m. Fiachach m. Feidelmid m. Cincce m. Guaire m. Cintae m. Coirpri Rigfhota
  26. ^ Dobbs 1921, pp. 330–1
  27. ^ The extant genealogy of the historical Dáirine, the Corcu Loígde, is corrupt for the early generations. They have been placed here by scholars. See Pokorny 1918.
  28. ^ see also O'Donovan, pp. 57, 86
  29. ^ Book of Ballymote
  30. ^ following Rawlinson B 502 and Laud 610
  31. ^ a b Laud 610 variant
  32. ^ Rawlinson B 502 variant


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