c.805 - King Egbert of Wessex formally establishes kingship over the people of Devon after a gradual integration over many years. Dumnonia is reduced to cover only the Cornish in Kernow (Cornwall). Death of Kings Gwrgauarn & Athrwys of Gwent. They are succeeded by the latter's son, Ithel.

806 - The Cornish call on the Vikings to help fight the Anglo-Saxons.

807 - Death of of King Arthen of Seisyllwg. He is succeeded by his son, Dyfnwal.

808 - Death of King Rhain of Dyfed. He is succeeded by his brother, Owain. Death of King Cadell of Powys. He is succeeded by his son, Cyngen.

809 - Death of Bishop Elfoddw of Bangor. His successor is unknown.

810 - Mynyw (St. David's) is burnt.

c.810 - Death of Kng Arthfael of Glywysing. He is succeeded by his son, Rhys.

811 - Death of King Owain of Dyfed. He is probably succeeded by his nephew, Triffyn.

812 - Degannwy, the capital of Gwynedd, is struck by lighning and burnt to the ground.

813 - King Cynan Dindaethwy of Gwynedd meets Hywel Farf-Fehinog in battle. Hywel is defeated.

814 - Prince Gruffudd of Powys is slain through the treachery of his brother Elisedd. Hywel Farf-Fehinog invades Anglesey and attacks his rival, King Cynan Dindaethwy of Gwynedd. Hywel is victorious, proclaims himself King and drives Cynan from the Gwynedd shores. Death of King Triffyn of Dyfed. It is not clear who takes on the Throne but it may have been seized by Bledrig, a low-born individual who had married Triffyn's cousin, Tangwystl.

815 - The Kingdom of Kernow (Cornwall) is raided by King Egbert of Wessex and his Saxon armies from East to West.

816 - King Hywel Farf-Fehinog of Gwynedd is attacked by his rival, King Cynan Dindaethwy, on Anglesey. Cynan is killed. The English successfully invade Rhufoniog and also ravage the Snowdonia Mountains.

c.816 - Death of King Riderch of Strathclyde. He is succeeded by his son, Dumnagual.

817 - The Battle of Llanfaes, possibly the result of another Anglo-Saxon incusion.

818 - King Coenwulf of Mercia raids Dyfed.

820 - Death of King Gruffudd of Brycheiniog. He is succeeded by his son, Tewdwr.

821 - King Coenwulf of Mercia dies in Basingwerk while preparing for another assault on Powys.

823 - The Mercians invade Powys, but are beaten back by King Cyngen. They also destroy the Gwynedd capital, Degannwy.

825 - Death of King Hywel Farf-Fehinog of Gwynedd. The kingdom is seized by King Merfyn Frych of Ynys Manaw (and South Rheged), grandson of his old rival, King Cynan Dindaethwy. The men of Kernow (Cornwall) make a push into Anglo-Saxon Devon and the two armies clash at the Battle of Gafelford (more likely Galford than Camelford). The Cornish are probably victorious.

c.830 - Nynnio, Abbot of Bangor Fawr, compiles the Historia Brittonum. Death of King Dyfnwal of Seisyllwg. He is succeeded by his son, Meurig.

831 - Death of Bishop Sadyrnfyw of Mynyw (St. David's). He is succeeded by Bishop Cadell.

836 - With King Merfyn Frych of Ynys Manaw absent in his newly acquired Kingdom of Gwynedd, Irish Viking invaders manage to take over the island.

838 - The British of Kernow (Cornwall) join forces with the Vikings and attack Saxon Wessex. King Egbert chases them back into the West and defeats them at the Battle of Hingston Down.

840 - Nobis is appointed Bishop of Mynyw (St. David's).

c.840 - Death of King Rhys of Glywysing. He is succeeded by his brother, Meurig. Grecielis is appointed Bishop of Gwent & Ergyng.

844 - Death of King Merfyn Frych of Gwynedd. His son, Rhodri Mawr, succeeds to the Throne. Battle of Cedyll, apparently unconnected.

c.844 - Death of King Dumnagual of Strathclyde. He is succeeded by his son, Artgal.

848 - The armies of Brycheiniog, presumably under King Tewdwr, and Gwent clash at the Battle of Ffinnant. King Ithel of Gwent is killed in the fighting. His cousin, King Meurig of Glywysing, re-establishes his family's control of Gwent.

849 - Death of King Meurig of Glywysing & Gwent. He is succeeded by his nephew, Hywel, who erects the 'Houelt Cross' at Llantilltud Fawr to the memory of his father, Rhys. The Britons of Strathclyde burn Dunblane.

c.850 - The 'Pillar of Eliseg' is erected in Llantysilio-yn-Ial by King Cyngen of Powys as a memorial to his great grandfather King Elisedd (or Eliseg) and the power of the Powysian dynasty. Bishop Censteg of Dingerein in Kernow (Cornwall) accepts the authority of Archbishop Ceolnoth of Canterbury. King Rhodri Mawr of Gwynedd develops Llanbedrgoch, and possibly other sites, as fortified settlements to protect the Welsh against Viking raids. Death of King Meurig of Seisyllwg. He is succeeded by his son, Gwrgon. Hyfaidd succeeds to the Throne of Dyfed, possibly due to the death of his father, Bledrig. Death of King Tewdwr of Brycheiniog. He is succeeded by his son, Elisedd.

853 - The armies of Kings Burghred of Mercia and Aethelwulf of Wessex attack Powys and Gwynedd in order to assert the overlordship of Mercia on Wales.

854 - King Cyngen of Powys dies on a pilgrimage to Rome. His throne is seized by his nephew, King Rhodri Mawr of Gwynedd, and his sons expelled.

855 - Anglesey is ravaged by Dublin Vikings.

856 - King Rhodri Mawr of Gwynedd & Powys repels a major Viking invasion of Wales and kills their king, Gorm.

c.860 - Death of Bishop Grecielis of Gwent & Ergyng. He is succeeded by Bishop Gwodloyw.

c.862 - Cerenhir is appointed Bishop of Llandeilo Fawr.

c.867 - Death of Bishop Gwodloyw of Gwent & Ergyng. He is succeeded by Bishop Hedilfyw.

c.868 - Death of Prince Ffernfael of Glywsing & Gwent. His cousin, King Hywel of Glywsing & Gwent hands over control of Gwent to Ffernfael's brother, Brochwel.

870 - Dumbarton Rock, capital of King Artgal of Strathclyde, is put under a four month siege by Kings Olaf Conung & Ivarr of Norse Dublin and their Viking warriors. The British eventually capitulate.

871 - Kings Olaf Conung & Ivarr of Norse Dublin return home from besieging Dumbarton Rock with many prisoners, including King Artgal of Strathclyde.

872 - Death of King Gwrgon of Seisyllwg by drowning. The Throne is taken by his brother-in-law, King Rhodri Mawr of Gwynedd & Powys. King Artgal of Strathclyde is slain by King Olaf Conung of Norse Dublin, through the connivance of his ally, King Constantine I of Alba (Scotland). Constantine marries his sister to Artgal's son, Run, who then succeeds to the Strathclyde Throne.

c.872 - King Hyfaidd of Dyfed expels Bishop Nobis from Mynyw (St. David's) and replaces him with Bishop Idwal. Death of Bishop Cerenhir of Llandeilo Fawr. Nobis becomes Bishop there instead.

c.873 - Bishop Nobis probably moves his cathedra from Llandeilo Fawr Cathedral to the abbey at Llandaff in order to avoid interference from Kings Hyfaidd of Dyfed and Rhodri Mawr of Seisyllwg (& Gwynedd & Powys).

874 - Death of Bishop Nobis of Llandaff. He is succeeded by Bishop Nudd.

876 - Death of Dungarth, the last King of Kernow (Cornwall). He is drowned during a hunting accident and buried at St. Cleer. The 'Doniert Stone' is erected to his memory.

877 - The Vikings invade Wales once more and King Rhodri Mawr of Gwynedd, Powys & Seisyllwg is defeated at the Battle of Anglsey (or Sunday Battle). With the royal court, he is forced to flee to Ireland.

878 - King Rhodri Mawr of Gwynedd, Powys and Seisyllwg returns to his kingdoms, but he and his son/brother, Gwriad, are killed fighting the Mercians of King Ceolwulf II. His kingdoms are divided amongst his three sons, Anarawd, Merfyn and Cadell respectively. The Vikings winter in Dyfed. Death of King Run of Strathclyde. His son, Eochaid, succeeds to the Throne and allies himself with his mother's cousin, King Giric of Alba (Scotland). The two rule all Scotland together as joint-monarchs.

880 - King Aethlered II of Mercia and his army make a daring incursion deep into Gwynedd. King Anarawd of Gwynedd defeats them at the Battle of the River Conwy.

c.881 - King Anarawd of Gwynedd and his brothers begin extensive military campaigns to quell resistance in Powys and Seisyllwg.

c.882 - Death of Bishop Nudd of Llandaff. He is succeeded by Abbot Cyfeiliog of Llanilltud Fawr.

885 - Bishop Asser of Mynyw (St. David's), is summoned to the court of King Alfred of Wessex, having been expelled from his diocese by King Hyfaidd of Dyfed. He agrees to spend six months of the year in England and six in Wales. Asser helps to enhance the literary status of the English Court and also to negotiate the recognition of Alfred as overlord of the South Welsh Kings.

c.885 - Kings Hyfaidd of Dyfed, Elisedd of Brycheiniog, Hywel of Glywysing and Brochwel & Ffernfael of Gwent are harassed by the armies of Kings Anarawd of Gwynedd and Aethelred II of Mercia. They seek the protection of King Alfred of Wessex and submit to his overlordship. Bishop Asser is perhaps allowed back to Mynyw (St. David's). King Anarawd seeks an alliance with the Norse Kings of York.

886 - Death of King Hywel of Glywysing. He is succeeded by his son, Arthfael.

889 - Kings Eochaid and Giric of Alba (Scotland), Strathclyde & the Picts are deposed by Viking invaders. The former's maternal cousin takes the Alban (Scottish) Throne as King Donald II. The end of independent Strathclyde rule. King Dumnagual is installed as sub-King of Strathclyde. His parentage is unknown but he appears to have been a member of the old royal family, possibly an uncle of King Eochaid.

890 - King Donald II of Alba (Scotland) expels the British aristorcracy from Strathclyde. They flee south to North Wales. King Anarawd of Gwynedd grants them land between the Dee and the Conwy in return for removing any Anglo-Saxons there

c.890 - Death of King Elisedd of Brycheiniog. He is succeeded by his son, Tewdwr.

893 - Death of King Hyfaidd of Dyfed. He is succeeded by his son, Rhodri. The Battle of Buttington takes place, just east of Welshpool in Powys, at which the Welsh under King Merfyn of Powys, and the English under King Alfred the Great, besiege and defeat the Viking army of Prince Hastein.

c.893 - Asser, the Welshman, is made Bishop of Sherborne. He also remains, at least nominally, Bishop of Mynyw (St. David's).

894 - King Anarawd of Gwynedd's shaky alliance with the Vikings collapses. His kingdom is ravaged by the Norsemen. Anarawd is forced to ask for help from King Alfred of Wessex and submits to his overlordship. Alfred imposes oppressive terms and forces Anarawd to confirmation in the Christian Church with Alfred as godfather. Bishop Asser of Sherborne & Mynyw (St. David's) writes his 'Life of King Alfred'

895 - King Anarawd of Gwynedd is supplied with English troops to assist in his reconquest of Seisyllwg. He is successful and his brother, King Cadell, is finally able to take his rightful place on the Seisyllwg Throne.

896 - Builth, Brycheiniog, Morgannwg, Gwynllwg and Gwent are ravaged by Haesten and his Viking pirate army.

c.900 - King Tewdwr of Brycheiniog establishes his court on a crannog in the middle of Llangorse Lake. Llanbedrgoch transforms from a fortified settlement into a trading centre. Death of Bishop Hedilfyw of Gwent & Ergyng. The diocese probably merges with that of Llandaff.

902 - The Norsemen are expelled from Dublin. They attempt to settle in Seisyllwg, but are driven off northwards.

903 - The Dublin Vikings, under Prince Ingimund, capture Osfeilion in Anglesey, but are quickly repulsed by Prince Clydog and settle in the Wirral and around Kelston & Axton in Flintshire instead.

904 - Marriage of Prince Hywel Dda of Seisyllwg to Princess Elen of Dyfed. Death of the latter's father, King Llywarch. The Throne of Dyfed is claimed by Llywarch's brother, Rhodri, but he is probably forced to flee from Hywel's armies.

905 - Rhodri, nominally King of Dyfed, is caught and executed, at Arwystli, probably by his niece's husband, Hywel Dda. Hywel claims the throne of Dyfed. Norse settlers from Flintshire and the Wirral attack the city of Chester, but are beaten off.

c.906 - Asser retires as Bidhop of St David's. He is succeeded by Bishop Arthfael.

909 - Death of Asser, the Welsh Bishop of Sherborne.