Question: What Brittonic dialect was spoken in the kingdom who had the father of Owain mab Urien as king?

full_context: Document 1: Kingdom of Strathclyde: Strathclyde (lit. "Strath of the River Clyde"), originally Cumbric: Ystrad Clud or Alclud (and Strath-Clota in Anglo-Saxon), was one of the early medieval kingdoms of the Britons in "Hen Ogledd" ("the Old North"), the Brythonic-speaking parts of what is now southern Scotland and northern England. The kingdom developed during the post-Roman period. It is also known as Alt Clut, a Brittonic term for Dumbarton Castle, the medieval capital of the region. It may have had its origins with the Brythonic Damnonii people of Ptolemy's "Geography".
Document 2: Ywain: Sir Ywain , also called Owain, Yvain, Ewain or Uwain, is a Knight of the Round Table and the son of King Urien and Morgan le Fay in Arthurian legend. The historical Owain mab Urien, on whom the literary character is based, was the king of Rheged in Great Britain during the late 6th century.
Document 3: Music of Northumbria: Here Northumbria is taken to mean Northumberland, the northernmost county of England, and County Durham. This area, together with Tweeddale, was the ancient British tribal kingdom of Bernicia (Bryneich) and is notable for the stable ancestry of its present indigenous population, which has been identified by DNA analysis to be an offshoot of the group Scotland, Cumbria and the North of Ireland, but not so closely related to the other peoples of the UK. The area was the core of the outstanding artistic culture that developed during the Northumbrian Golden Age of the 7th and 8th centuries; it would be unwise to suggest that the area did not have a flourishing musical culture at that time, or that it was not of similar sophistication - Bede makes reference to the playing of the harp. The traditional music of this area may be a tangible legacy of the Bernicians - given that little is known of the antiquity of Northumbrian music; though traditional Northumbrian instruments would have had their limitations. However, much surviving early modern Northumbrian music is similar in form to the music of the Scottish Lowlands, so Northumberland's position on the cultural frontier between England and Scotland has played a significant role. The modern era has seen Northumbrian traditional music artificially pigeon holed into national divisions, into which Northumbrian music simply will not fit. Likewise, the crude assumption that the font of all music of substance was in the west and north of the British isles has undermined considered appreciation of the local repertoire.The region possesses a distinctive style of folk music with a strong and continuing tradition. The region is particularly noted for its tradition of border ballads, the Northumbrian smallpipe (a form of bagpipe unique to north-east England) and also a strong fiddle tradition in the region that was already well established in the 1690s. Northumbrian music is characterised by considerable influence from other regions (and vice versa), particularly southern Scotland and other parts of the north of England. Irish tunes are also much played in the region, as they are elsewhere. There has been a continuous tradition of traditional and distinctive Northumbrian styles since the 18th century – there have also been 'revivals' in the late nineteenth century and again in the mid-twentieth. More recently, Northumbrian folk music, and particularly the use of the Northumbrian pipes, has become one of the liveliest and most widely known forms of folk music in Britain.
Document 4: Meirchion Gul: Meirchion Gul was probably a late 5th-century king of Rheged, a Brythonic realm in the area of sub-Roman known as the "Hen Ogledd" (in the North of England and Southern Scotland today).
Document 5: Hen Ogledd: Yr Hen Ogledd (] ), in English the Old North, is the region of Northern England and the southern Scottish Lowlands inhabited by the Celtic Britons of sub-Roman Britain and the Early Middle Ages. Its denizens spoke a variety of the Brittonic language known as Cumbric. The Hen Ogledd was distinct from the parts of northern Britain inhabited by the Picts, Anglo-Saxons, and Scoti as well as from Wales, although the people of the Hen Ogledd were the same Brittonic stock as the Picts, Welsh and Cornish, and the region loomed large in Welsh literature and tradition for centuries after its kingdoms had disappeared.
Document 6: Owain mab Urien: Owain mab Urien (or Owein) (died c. 595) was the son of Urien, king of Rheged c. 590, and fought with his father against the Angles of Bernicia. The historical figure of Owain became incorporated into the Arthurian cycle of legends where he is also known as Ywain, Yvain, Ewain or Uwain. In his legendary guise he is the main character in Chrétien de Troyes's "Yvain, the Knight of the Lion" and the Welsh Romance "Owain, or the Lady of the Fountain", which corresponds to Chrétien's poem.
Document 7: Owain ap Dyfnwal (died 1015): Owain ap Dyfnwal (died 1015) may have been an eleventh-century ruler of the Kingdom of Strathclyde. He seems to have been a son of Dyfnwal ab Owain, King of Strathclyde, and may well have succeeded Dyfnwal's son, Máel Coluim, King of Strathclyde. During Owain's reign, he would have faced a massive invasion by Æthelræd II, King of the English. Owain's death is recorded in 1015, and seems to have been succeeded by Owain Foel, a man who may have been his nephew.
Document 8: Northumbrian dialect: Northumbrian was a dialect of Old English spoken in the Anglian Kingdom of Northumbria. Together with Mercian, Kentish and West Saxon, it forms one of the sub-categories of Old English devised and employed by modern scholars.
Document 9: Urien: Urien , often referred to as Urien Rheged or Uriens, was a late 6th-century king of Rheged, an early British kingdom of the "Hen Ogledd" (northern England and southern Scotland). His power and his victories, including the battles of Gwen Ystrad and Alt Clut Ford, are celebrated in the praise poems to him by Taliesin, preserved in the "Book of Taliesin". He became the "King Urien of Gorre" of later Arthurian legend and his son Owain mab Urien was later known as Ywain.
Document 10: Battle of Argoed Llwyfain: The Battle of Argoed Llwyfain was fought between the forces of the Kingdom of Rheged under the command of Urien and Owain mab Urien and the forces of the Kingdom of Bernicia under "Fflamddwyn" (Firestealer or Flamebearer).
Document 11: Bonedd Gwŷr y Gogledd: Bonedd Gwŷr y Gogledd (English: The Descent of the Men of the North ) is a brief Middle Welsh tract which claims to give the pedigrees of twenty 6th century rulers of the Hen Ogledd, the Brittonic-speaking parts of southern Scotland and northern England. It is attested in a number of manuscripts, the earliest being NLW, Peniarth MS 45, which has been dated to the late 13th century. The text may have been composed in the 12th century. The historicity of much of the information is spurious or in doubt. Although certain parts are in agreement with the earlier Harleian genealogies, the text represents a substantial revision seeking to integrate the branches of many rulers and heroes who are prominent in other traditions, such as the Rheged prince Llywarch Hen.
Document 12: Rheged: Rheged (] ) was one of the kingdoms of the "Hen Ogledd" ("Old North"), the Brittonic-speaking region of what is now Northern England and southern Scotland, during the post-Roman era and Early Middle Ages. It is recorded in several poetic and bardic sources, although its borders are not described in any of them. Some modern scholars have suggested that it included what is now Cumbria in North West England and possibly extended into Lancashire and Scotland. In some sources, Rheged is intimately associated with the king Urien Rheged and his family. Its inhabitants spoke Cumbric, a Brittonic dialect closely related to Old Welsh.
Document 13: Kingdom of Northumbria: The Kingdom of Northumbria ( ; Old English: "Norþhymbra rīce" , "kingdom of the Northumbrians") was a medieval Anglian kingdom in what is now northern England and south-east Scotland, which subsequently became an earldom in a unified English kingdom. The name reflects the approximate southern limit to the kingdom's territory, the Humber estuary.
Document 14: Uther Pendragon: Uther Pendragon ( ; Welsh: "Uthyr Pendragon, Uthyr Bendragon" ) also known as King Uther, is a legendary king of sub-Roman Britain and the father of King Arthur. A few minor references to Uther appear in Old Welsh poems, but his biography was first written down by Geoffrey of Monmouth in his "Historia Regum Britanniae" ("History of the Kings of Britain"), and Geoffrey's account of the character was used in most later versions.
Document 15: Owain Foel: Owain Foel (fl. 1018), also known as Owen the Bald, and Eugenius Calvus, was an eleventh-century King of Strathclyde. He may have been a son of Máel Coluim, son of Dyfnwal ab Owain, two other rulers of the Kingdom of Strathclyde. Owain Foel is recorded to have supported the Scots at the Battle of Carham in 1018. Although it is possible that he died in the conflict, no source states as much, and it is uncertain when he died. Owain Foel may be an ancestor—perhaps the father—of a certain Máel Coluim who is described as the "son of the king of the Cumbrians" in the 1050s.
ground_truth: Cumbric