Eochaid ab Rhun (fl. 853-889) was a ninth century King of Strathclyde, who may have also been King of the Picts. He was a son of Rhun ab Arthgal, King of Strathclyde, and descended from a long line of British kings. Eochaid's mother is recorded to have been a daughter of Cináed mac Ailpín, King of the Picts. This maternal descent from the royal Alpínid dynasty may well account for the record of Eochaid reigning over the Pictish realm after the death of Cináed's son, Áed, in 878. According to various sources, Áed was slain by Giric, whose ancestry is uncertain and who then proceeded to usurp the Alban throne. Eochaid was posthumously given the epithet "In Tuilti" by the Prophecy of Saint Berchán.Skene, Chronicles, p. 87.

Heir to the Brythonic kingdom of Strathclyde and a claimant to the Gaelic throne of the Picts, Eochaid was of mixed blood. Indeed, the name Eochaid is Gaelic and may indicate his maternal descent from the Alpínid dynasty. It is uncertain if Eochaid and Giric were relatives, unrelated allies, or even rivals. Whilst it is possible that they held the Pictish kingship concurrently as allies, it is also conceivable that they ruled successively as opponents. Another possibility is that, whilst Giric reigned as King of the Picts, Eochaid reigned as King of Strathclyde. Eochaid's floruit dates about the time when the Kingdom of Strathclyde seems to have expanded southwards into lands formerly possessed by the Kingdom of Northumbria. The catalyst for this extension of British influence appears to have been the Viking conquest of this northern English realm.

According to various sources, Eochaid and Giric were driven from the kingship in 889. The succeeding king, Domnall mac Custantín, was an Alpínid, and could well have been responsible for the forced regime change. The terminology employed by various sources suggests that during the reigns of Eochaid and Giric, or during that of Domnall and his successors, the wavering Pictish kingdom — weakened by political upheaval and Viking invasions — redefined itself as a Gaelic realm: the Kingdom of Alba.

Eochaid is not attested after 889. Likewise, nothing is recorded of the Kingdom of Strathclyde until the first quarter of the next century, when a certain Dyfnwal, King of Strathclyde is reported to have died. Whilst the parentage of this man is unknown, it is probable that he was a member of Eochaid's kindred, and possibly a descendant of him. A daughter of Eochaid may have been Lann, a woman recorded to have been the mother of Muirchertach mac Néill, King of Ailech.

Ancestors

Eochaid was a son of Rhun ab Arthgal, King of Strathclyde.Clarkson (2014) ch. genealogical tables; Charles-Edwards (2013b) p. 572 fig. 17.4; Walker (2013) ch. family trees tab. 5; Clarkson (2012a) ch. appendix a; Clarkson (2012b) ch. genealogical tables; Clarkson (2010) ch. genealogical tables; Broun (2004d) p. 135 tab.; Lynch (2001) p. 680 tab.; Macquarrie (1998) p. 6 tab.; Duncan (1996) pp. 628–629 genealogical tree 1; Collingwood (1920) p. 56 tab. Rhun's patrilineal ancestry is evidenced by a pedigree preserved within a collection of tenth century Welsh genealogical material known as the Harleian genealogies. According to this source, he was descended from a long line of kings of Al Clud.Guy (2016) pp. 6 tab. 1, 22–23; Clarkson (2014) chs. genealogical tables, 1 ¶ 23, 2 ¶ 21; Clarkson (2010) chs. genealogical tables, introduction ¶ 12, 2 ¶ 35; Broun (2004d) p. 117; Dumville, DN (1999) p. 110; Ó Corráin (1998a) § 38; Ó Corráin (1998b) p. 331; Woolf (1998) pp. 159–160; Williams; Smyth; Kirby (1991) p. 134; Macquarrie (1990) p. 7; Anderson, AO (1922) pp. clvii–clviii; Phillimore (1888) pp. 172–173; Skene (1867) p. 15. The ninth to twelfth century Chronicle of the Kings of Alba evinces that Rhun was married to a daughter of Cináed mac Ailpín, King of the Picts,Edmonds (2015) p. 60; Anderson, MO (2010) p. 123; Bartrum (2009) p. 286; Downham (2007) p. 163; Bhreathnach (2005) p. 269; Broun (2004d) p. 127; Hudson, BT (1996) p. 206; Hudson, BT (1998) pp. 149, 154; Ó Corráin (1998a) § 38; Ó Corráin (1998b) p. 331; Hudson, BT (1994) pp. 52, 55, 164 tab. 2a, 173 genealogy 6, 174 n. 3; Anderson, AO (1922) p. 363; Skene (1867) p. 9. and states that a product of the union was Eochaid himself.Bartrum (2009) pp. 286, 642; Clancy (2006b); Davidson (2002) p. 126; Hudson, BT (2002) p. 48; Woolf (2000) p. 147 n. 8; Macquarrie (1998) p. 13; Hudson, BT (1998) pp. 149, 154; Smyth (1989) p. 217; Anderson, AO (1922) p. 363; Skene (1867) p. 9. Eochaid's maternal ancestry may be exemplified in the name he bore.Edmonds (2015) p. 60; Oram (2011) ch. 2. There is no known British form of the Gaelic . In theory, a Pictish form of the name would be * or *.Woolf (2007) pp. 62–63, 63 n. 32.

In 870, during the reign of Rhun's father, Arthgal ap Dyfnwal, King of Al Clud, the fortress of Al Clud was captured and destroyed by the insular Scandinavian kings Amlaíb and Ímar.Jorgensen (2017) 48, 48 n. 145; The Annals of Ulster (2017) § 870.6; McLeod, S (2015) pp. 3, 11; Edmonds (2014) p. 200; Hudson, B (2014) p. 203; Charles-Edwards (2013b) p. 480; Downham (2013) p. 17; Walker (2013) ch. 1 ¶ 40; Fraser (2012) p. 71; Downham (2011) p. 192; Gigov (2011) p. 23; McLeod, SH (2011) pp. 123–124; Clarkson (2010) ch. 8 ¶ 20; Fragmentary Annals of Ireland (2010) § 388; Davies (2009) p. 73, 73 n. 35; Ó Corráin (2008) p. 430; Fragmentary Annals of Ireland (2008) § 388; The Annals of Ulster (2008) § 870.6; Downham (2007) pp. 66–67, 142, 240, 258; Woolf (2007) p. 109; Forte; Oram; Pedersen (2005) p. 88; Costambeys (2004); Valante (1998–1999) p. 245; Hicks (2003) p. 34; Driscoll, ST (1998a) p. 112; Macquarrie (1998) p. 12; Ó Corráin (1998a) § 38, 38 n. 141; Ó Corráin (1998b) p. 331, 331 n. 149; Crawford (1997) p. 50; Hudson, BT (1994) p. 50; Smyth (1989) p. 215; Holm (1986) p. 321; Brooks (1979) p. 6; Alcock (1975–1976) p. 106; McTurk (1976) p. 117 n. 173; Anderson, AO (1922) pp. 301–302; Beaven (1918) p. 337 n. 36. In the following year, Amlaíb and Ímar returned to Ireland with a fleet of two hundred ships, and a mass of captives identified as English, British, and Pictish.Downham (2018) p. 49; The Annals of Ulster (2017) § 871.2; Wadden (2016) p. 176; McLeod, S (2015) pp. 3, 11; Edmonds (2014) p. 200; Hudson, B (2014) p. 204; Downham (2013) p. 17, 17 n. 38; Chronicon Scotorum (2012) § 871; Downham (2011) p. 192; Gigov (2011) p. 23; McLeod, SH (2011) pp. 123–124, 171–172 n. 339; Chronicon Scotorum (2010) § 871; Clarkson (2010) ch. 8 ¶ 20; Fragmentary Annals of Ireland (2010) § 393; Fragmentary Annals of Ireland (2008) § 393; Ó Corráin (2008) p. 430; Sheehan (2008) p. 289; The Annals of Ulster (2008) § 871.2; Broun (2007) p. 80; Downham (2007) pp. 22–23, 66–67, 142, 240, 259; Woolf (2007) p. 109; Forte; Oram; Pedersen (2005) p. 88; Costambeys (2004); Hicks (2003) p. 34; Hudson, BT (2002) p. 33; Sawyer (2001) p. 10; Kelly; Maas (1999) p. 144; Driscoll, ST (1998a) p. 112; Macquarrie (1998) p. 12; Ó Corráin (1998a) § 38, 38 n. 142; Ó Corráin (1998b) p. 331, 331 n. 150; Hudson, BT (1994) p. 51; Ó Murchadha (1992–1993) p. 59; Smyth (1989) p. 215; Holm (1986) p. 321, 321 n. 10; Pelteret (1980) p. 106, 106 n. 64; Ó Corráin (1979) p. 319; Alcock (1975–1976) p. 106; Anderson, AO (1922) pp. 302–303, 303 n. 1. Arthgal died in 872.Guy (2016) p. 5 n. 15; Edmonds (2015) p. 60; Evans (2015) p. 150; Clarkson (2014) ch. 3 ¶ 11; Edmonds (2014) p. 200; Walker (2013) ch. 1 ¶ 42; Woolf (2010) p. 225; Bartrum (2009) p. 29; Downham (2007) p. 163; Clancy (2006a); Clancy (2006c); Calise (2002) p. 197; Hicks (2003) pp. 16, 30; Dumville, DN (1999) pp. 110–111; Macquarrie (1998) p. 12; Ó Corráin (1998a) § 38; Ó Corráin (1998b) p. 331; Hudson, BT (1994) pp. 52, 174 n. 1. The Annals of UlsterThe Annals of Ulster (2017) § 872.5; Edmonds (2015) p. 60; Evans (2015) p. 150; Clarkson (2014) ch. 3 ¶ 11, 3 n. 10; Edmonds (2014) p. 200; Walker (2013) ch. 1 ¶ 42; Woolf (2010) p. 225; Bartrum (2009) p. 29; Clancy (2009) p. 28; Davies (2009) p. 73, 73 n. 36; The Annals of Ulster (2008) § 872.5; Downham (2007) p. 163; Clancy (2006a); Clancy (2006c); Hicks (2003) pp. 16, 30; Calise (2002) p. 197; Hudson, BT (2002) p. 41; Dumville, DN (1999) pp. 110–111; Macquarrie (1998) p. 12; Hudson, BT (1994) pp. 52, 174 n. 1; Ó Murchadha (1992–1993) p. 60; Macquarrie (1990) p. 7; Anderson, AO (1922) p. 304. and Chronicon Scotorum reveal that he was slain at the behest of Rhun's brother-in-law, Custantín mac Cináeda, King of the Picts.Edmonds (2015) p. 60; Evans (2015) p. 150; Edmonds (2014) p. 200; Chronicon Scotorum (2012) § 872; Chronicon Scotorum (2010) § 872; Calise (2002) p. 197; Anderson, AO (1922) p. 304 n. 2. The circumstances surrounding Arthgal's assassination are unknown,Clancy (2006a); Hudson, BT (1994) p. 52. and Rhun's reign probably commenced not long after his death.Clarkson (2014) ch. 3 ¶ 23; Woolf (2007) p. 111.

Prior to its fall, the fortress of Al Clud served as the capital of Arthgal's Kingdom of Al Clud, and afterwards the capital appears to have relocated up the River Clyde to the vicinity of GovanFoley (2017); Driscoll, ST (2015) pp. 5, 7; Clarkson (2014) chs. 1 ¶ 23, 3 ¶ 11–12; Edmonds (2014) p. 201; Charles-Edwards (2013b) pp. 9, 480–481; Clarkson (2012a) ch. 8 ¶ 23; Clarkson (2012b) ch. 11 ¶ 46; Clarkson (2010) ch. 8 ¶ 22; Davies (2009) p. 73; Oram (2008) p. 169; Downham (2007) p. 169; Clancy (2006c); Driscoll, S (2006); Forsyth (2005) p. 31; Ewart; Pringle; Caldwell et al. (2004) pp. 8, 10; Driscoll, ST (2003) pp. 81–82; Hicks (2003) pp. 32, 34; Driscoll, ST (2001a); Driscoll, ST (2001c); Driscoll, ST (1998a) p. 112. and Partick.Driscoll, ST (2015) pp. 5, 7; Clarkson (2014) ch. 3 ¶ 13; Clarkson (2012a) ch. 8 ¶ 23; Clarkson (2012b) ch. 11 ¶ 46; Clarkson (2010) ch. 8 ¶ 22; Ewart; Pringle; Caldwell et al. (2004) pp. 8, 10. The relocation is partly exemplified by a shift in royal terminology. Until the fall of Al Clud, for example, the rulers of the realm were styled after the fortress; whereas following the loss of the site, the Kingdom of Al Clud came to be known as the Kingdom of Strathclyde in consequence to its reorientation towards Ystrad Clud (Strathclyde), the valley of the River Clyde.Driscoll, ST (2015) p. 5; Clarkson (2014) ch. 3 ¶ 11; Edmonds (2014) pp. 200–201; Clarkson (2012a) ch. 8 ¶ 23; Clarkson (2012b) ch. 11 ¶ 46; Clarkson (2010) ch. 8 ¶ 26; Downham (2007) p. 162 n. 158; Clancy (2006c); Ewart; Pringle; Caldwell et al. (2004) pp. 8, 10; Hicks (2003) pp. 15, 16, 30. Either Arthgal or Rhun could have been the first monarch to rule the reconstructed realm of Strathclyde.Clarkson (2014) chs. 1 ¶ 23, 3 ¶ 18.