The original
Celtic chiefs of the
Dumnonii ruled in the south-west corner of the British Isles until faced with the arrival of the
Romans in their territory in c. AD 55, when the Romans established a legionary fortress at
Isca Dumnoniorum (modern
Exeter). Although subjugated by c. AD 78, the
civitas Dumnoniorum was among the regions of
Roman Britain least affected by Roman influence. Known as Caer Uisc, Exeter was inhabited by Dumnonian Britons until c. 936, when
King Athelstan expelled them. Several other royal residences may also have served the kings of Dumnonia or Cornwall, including
Tintagel as the principal one and
Cadbury Castle as a temporary one, which also served the purpose of defence. ;Legendary 'Dukes of Cornwall' recorded by
Geoffrey of Monmouth: •
Caradoc ( 290 – c. 305) •
Donault, brother of Caradoc (c. 305 – c. 340) ;Presumed kings appearing in the ancestries of later monarchs: •
Conan Meriadoc ap Gereint, '"Conan the Merry" (c. 340 – c. 387) • Gadeon ap Conan (c. 387 – c. 390) • Guoremor ap Gadeon (c. 387 – c. 400) • Tutwal ap Guoremor (c. 400 – c. 410) • Conomor ap Tutwal (c. 410 – c. 435) •
Constantine Corneu ap Conomar, "Constantine of Cornwall" (c. 435 – c. 443) ;Kings recorded in Welsh records and literature: •
Erbin ap Constantine (c. 443 – c. 480) •
Geraint Llyngesic ab Erbin, "Gerren the Fleet Owner" (c. 480 – c. 514) •
Cado ap Gerren (c. 514 – c. 530) • Custennin ap Cado, probably "
Saint Custennin" (c. 530 – c. 560) •
Gerren rac Denau ap Custennin, "Gerren for the South" (c. 560 – c. 598) ;William of Malmesbury: • Gwrgan:
William of Malmesbury reports the terms of a grant of land made by King Gwrgan of
Damnonia to the "old church" at
Glastonbury in AD 601 in the time of Abbot Worgret. ;Possible rulers given in the early 17th-century Book of Baglan as ancestors of an 'Earl of Cornwall' •
Bledric ap Custennin (c. 598 – c. 613) •
Clemen ap Bledric (c. 613 – c. 633) •
Petroc Baladrddellt ap Clemen, "Petroc Splintered Spear" (c. 633 – c. 654) • Culmin ap Petroc (c. 659 – c. 661) • Donyarth ap Culmin (c. 661 – c. 700) ;Kings recorded in
Anglo-Saxon sources: •
Geraint (c. 700 – c. 710) ;
Breton Princes of
Armorican Dumnonia, from the
Life of Saint Winnoc; see also
Domnonée. (The earlier portion follows the Dumnonian line beginning with Gereint, Cado, Erbin, Guitol ap Gradlon, Marchell, and
Riothamus) • Riwal (510–520) • Deroch (520–535), son of Riwal • Iona (535–540), son of Deroch • Judual (Judwal), son of Iona (540–545) •
Conomor (540–555), count of Poher, first regent, then usurper, possibly
Mark of Cornwall • Judwal (555–580, re-established) • Judaël (580–605), older son of Judwal • Haëloc (605–610), younger son of Judaël •
Saint Judicael (r. 610–640, † 647/652), elder son of Judaël, abdicated • Judoc (r. 640–640, † 669), younger son of Judaël, renounced the throne • Saint
Winnoc (r. 640, † 717), possibly a son of Judicael, renounced the throne.
Native tradition Susan Pearce views the only native 4th- to 7th-century Dumnonian rulers known to history as: • Constantine (Welsh
Custennin Gorneu), mentioned in
De Excidio et Conquestu Britanniae • Erbin • Geraint (Welsh
Geraint fab Erbin) • Cadwy (Cado) Pearce identifies Constantine with the Constantine mentioned by
Gildas, anchoring his reign to the 6th century, and giving later dates for the reigns of Erbin, Geraint, and Cadwy. ==Cornish kings==