Eugein I was a ruler of Alt Clut

Kingdom of Strathclyde

Strathclyde , originally Brythonic Ystrad Clud, was one of the early medieval kingdoms of the celtic people called the Britons in the Hen Ogledd, the Brythonic-speaking parts of what is now southern Scotland and northern England. The kingdom developed during the post-Roman period...

 (modern Dumbarton Rock), the kingdom later known as Strathclyde, sometime in the mid-7th century. According to the Harleian genealogies

Harleian genealogies

The Harleian genealogies are a collection of Old Welsh genealogies preserved in British Library, Harleian MS 3859. Part of the Harleian Collection, the manuscript, which also contains the Annales Cambriae and a version of the Historia Brittonum, has been dated to c. 1100, although a date of c.1200...

, he was the son of Beli I

Beli I of Alt Clut

Beli I was a ruler of Alt Clut , the Brythonic kingdom later known as Strathclyde, some time in the 7th century. Very little is known of him, but his family appears to have been very well connected in northern Britain....

, presumably his predecessor as king, and the father of Elfin

Elfin of Alt Clut

Elfin was a ruler of Alt Clut, the Brythonic kingdom later known as Strathclyde, sometime in the later 7th century. According to the Harleian genealogies, he was the son of Eugein I, one of his predecessors as king, and the father of Beli II, who ruled some time later...

, who ruled sometime later. The Annals of Ulster

Annals of Ulster

The Annals of Ulster are annals of medieval Ireland. The entries span the years between AD 431 to AD 1540. The entries up to AD 1489 were compiled in the late 15th century by the scribe Ruaidhrí Ó Luinín, under his patron Cathal Óg Mac Maghnusa on the island of Belle Isle on Lough Erne in the...

and the Annals of Tigernach

Annals of Tigernach

The Annals of Tigernach is a chronicle probably originating in Clonmacnoise, Ireland. The language is a mixture of Latin and Old and Middle Irish....

record another probable son, Dumnagual

Dumnagual II of Alt Clut

Dumnagual II was a ruler of Alt Clut, the British kingdom later known as Strathclyde , for sometime in the late seventh century. He is known only from his death notice in the Irish annals. The Annals of Ulster, under the year 694, has Domnall m. Auin, rex Alo Cluathe, moritur...

, who ruled Alt Clut and died in 694. Eugein was probably the brother or half brother of Bridei III of the Picts

Bridei III of the Picts

King Bridei III was king of Fortriu and overking of the Picts between 671 and his death in 693....

, the victor at the Battle of Dun Nechtain.

The Annals of Ulster

Annals of Ulster

The Annals of Ulster are annals of medieval Ireland. The entries span the years between AD 431 to AD 1540. The entries up to AD 1489 were compiled in the late 15th century by the scribe Ruaidhrí Ó Luinín, under his patron Cathal Óg Mac Maghnusa on the island of Belle Isle on Lough Erne in the...

record that a Hoan or Oan, King of the Britons

King of the Britons

The Britons or Brythons were the Celtic-speaking people of what is now England, Wales and southern Scotland, whose ethnic identity is today maintained by the Welsh, Cornish and Bretons...

, defeated and killed Domnall Brecc

Domnall Brecc

Domnall Brecc was king of Dál Riata, in modern Scotland, from about 629 until 642...

 of Dál Riata

Dál Riata

Dál Riata was a Gaelic overkingdom on the western coast of Scotland with some territory on the northeast coast of Ireland...

 at a place called Srath Caruin (Strathcarron

Strathcarron

Strathcarron may refer to:*Baron Strathcarron*Strathcarron railway station*Strathcarron, Highland, a village in Scotland*the strath of the River Carron, Wester Ross*the strath of the River Carron *the strath of the River Carron, Sutherland...

) in 642. A stanza interpolated in the poem Y Gododdin

Y Gododdin

Y Gododdin is a medieval Welsh poem consisting of a series of elegies to the men of the Britonnic kingdom of Gododdin and its allies who, according to the conventional interpretation, died fighting the Angles of Deira and Bernicia at a place named Catraeth...

, often known as the "Strathcarron interpolation" or simply The Battle of Strathcarron, refers to these events, indicating that the forces of "Nwython's grandson" (i.e., Eugein, the grandson of Neithon of Alt Clut

Neithon of Alt Clut

Neithon was a 7th-century ruler of Alt Clut, the Brittonic kingdom later known as Strathclyde . According to the Harleian genealogies, he was the son of Guipno map Dumnagual Hen. Alfred Smyth suggests he is the same man as King Nechtan the Great of the Picts, and perhaps the Nechtan son of Canu...

) triumphed over "Dyfnwal Frych" (Domnall Brecc), the ruler of "Pentir" (Kintyre

Kintyre

Kintyre is a peninsula in western Scotland, in the southwest of Argyll and Bute. The region stretches approximately 30 miles , from the Mull of Kintyre in the south, to East Loch Tarbert in the north...

, or Dál Riata). Eugein's date of death is unknown, but he was certainly dead by 658, when another king of Alt Clut, Guret

Guret of Alt Clut

Guret was a ruler of Alt Clut, the Brythonic kingdom later known as Strathclyde, during the mid-7th century. He is known only from an obituary note in the Annals of Ulster, which records Mors Gureit regis Alo Cluathe under the year 658...

, has his death recorded by the Annals of Ulster. This Guret does not appear in the genealogies; he may have been a brother or son of Eugein.