Glywysing was, from the sub-Roman

Sub-Roman Britain

Sub-Roman Britain is a term derived from an archaeological label for the material culture of Britain in Late Antiquity: the term "Sub-Roman" was invented to describe the potsherds in sites of the 5th century and the 6th century, initially with an implication of decay of locally-made wares from a...

 period through to the Early Middle Ages

Early Middle Ages

The Early Middle Ages was the period of European history lasting from the 5th century to approximately 1000. The Early Middle Ages followed the decline of the Western Roman Empire and preceded the High Middle Ages...

, a petty kingdom

Petty kingdom

A petty kingdom is one of a number of small kingdoms, described as minor or "petty" by contrast to an empire or unified kingdom that either preceded or succeeded it...

 in south-east Wales

Wales

Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

. Its people were descended from the Iron Age tribe

Iron Age tribes in Britain

The names of the Iron Age tribes in Britain were recorded by Roman and Greek historians and geographers, especially Ptolemy, although information from the distribution of Celtic coins has also shed light on the extents of the territories of the various groups that occupied the island.It is...

 of the Silures

Silures

The Silures were a powerful and warlike tribe of ancient Britain, occupying approximately the counties of Monmouthshire, Breconshire and Glamorganshire of present day South Wales; and possibly Gloucestershire and Herefordshire of present day England...

.

Location and etymology

Glywysing is said to be named after Glywys

Glywys

Glywys is described in Welsh genealogies as an early 5th century Welsh king who is seen as an important character in early Welsh history. The kingdom of Glywysing is believed to have been named after Glywys, and is the earliest place name for the land between the Rivers Tawe and Usk...

, a real or legendary early monarch, whose name may continue that of the Romano-British *Glevenses, the territory and citizens of Glevum

Glevum

Glevum was a Roman fort in Roman Britain that become "colonia" of retired legionaries in AD 97. Today it is known as Gloucester, located in the English county of Gloucestershire...

, or Gloucester. According to twelfth century sources, after the death of Glywys the kingdom was divided into seven cantrefi named for his sons including Cydweli, Gwyr, Margam

Margam

Margam is a suburb of Port Talbot in the Welsh county borough of Neath Port Talbot, Wales, close to junction 39 of the M4 motorway.- History :...

, Penychen

Penychen

Penychen was a possible minor kingdom of early mediæval Wales and later a cantref of the Kingdom of Morgannwg. Penychen was one of three cantrefs that made up the kingdom of Glywysing, the other two being Gwynllwg and Gorfynydd...

, Gwynllwg

Gwynllwg

Gwynllŵg was a kingdom of mediæval Wales and later a Norman lordship and then a cantref.-Location:It was named after Gwynllyw, its 5th century or 6th century ruler and consisted of the coastal plain stretching between the Rhymney and Usk rivers, together with the hills to the north...

 and Gorfynydd

Gorfynydd

Gorfynydd was a cantref in Morgannwg, Wales lying between the rivers Thaw and Neath . The name survived in ecclesiastical use until recently as the rural deanery of Gronneath ....

, though the kingdom of Glwysing still existed. The borders changed over time, but it is generally thought that its lands originally lay between the Afon Llwyd

Afon Llwyd

The Afon Lwyd is a small river in south Wales which flows from its source north of Blaenavon, through Abersychan, Pontypool and Cwmbran before flowing into the River Usk at Caerleon, which subsequently flows into the Bristol Channel in Newport. The name is Welsh, meaning "Grey River".Historically...

 and the River Towy. At times they expanded eastwards to encompass both Gwent and Ergyng

Ergyng

Ergyng was a Welsh kingdom of the sub-Roman and early medieval period, between the 5th and 7th centuries. It was later referred to by the English as Archenfield.-Location:...

, but some time before the early 8th century, Cydweli and Gwyr (Gower)

Gower (Lordship)

thumb|350px|right|Map of the Lordship, showing the area detached , the area added and the Town and Franchise of Swansea. The language boundary is shown as a dotted line....

 were lost to Dyfed

Kingdom of Dyfed

The Kingdom of Dyfed is one of several Welsh petty kingdoms that emerged in 5th-century post-Roman Britain in south-west Wales, based on the former Irish tribal lands of the Déisi from c 350 until it was subsumed into Deheubarth in 920. In Latin, the country of the Déisi was Demetae, eventually to...

.
Today the area of Glywysing is known as Glamorgan

Glamorgan

Glamorgan or Glamorganshire is one of the thirteen historic counties and a former administrative county of Wales. It was originally an early medieval kingdom of varying boundaries known as Glywysing until taken over by the Normans as a lordship. Glamorgan is latterly represented by the three...

.

Part of the Kingdom of Morgannwg

In the mid 10th century, the kingdom merged with Gwent and changed its name to Morgannwg or Gwlad Morgan in honour of its king, Morgan Hen (942-74). Glywysing seems to have been a sub-kingdom or principality of the Kingdom of Morgannwg, along with Gwent.
After the death of Morgan Hen, Gwent and Glywysing were separated again from 974 to 1055, but Glywysing alone was often referred to as Morgannwg. Both areas were conququered by Gruffydd ap Llywelyn

Gruffydd ap Llywelyn

Gruffydd ap Llywelyn was the ruler of all Wales from 1055 until his death, the only Welsh monarch able to make this boast...

 in about 1055, but on his death in 1063, Morgannwg, the union between Gwent and Glywysing,
was reconstituted. How this occurred is unclear; possibly the Kings of Glywysing were also Kings of Morgannwg and the Kings of Gwent were semi-independent under-Kings. The last native ruler of these areas was Iestyn ap Gwrgan, King of Morgannwg (1081-1090), who was deposed by Robert Fitzhamon

Robert Fitzhamon

Robert Fitzhamon , or Robert FitzHamon, Sieur de Creully in the Calvados region and Torigny in the Manche region of Normandy, was Lord of Gloucester and the Norman conqueror of Glamorgan, southern Wales...

.