Dyfed
A minor kingdom in post-Roman Wales, called Deheubarth, also spelled Dyfed in some historical sources. Deheubarth was one of the traditional kingdoms in Wales.
The name Deheubarth translates to “the southern part” in Welsh, signifying its location in the southern region of Wales. It emerged as an independent kingdom during the early Middle Ages, and its rulers played significant roles in Welsh politics and history. The kingdom was formed through the unification of several smaller Welsh territories, promarily in the region of Dyfed.
The early rulers of Deheubarth were the descendants of Hywel Dda (Hywel the Good), a prominent Welsh king who is known for his codification of Welsh laws. Hywel Dda is considered one of the most influential rulers of Deheubarth.
KINGS OF DEHEUBARTH
Hywel Dda (the Good) | 909-950
Rhodri ap Hywel | 950-953 (joint)
Edwin ap Hywel | 950-954 (joint)
Owain ap Hywel | 950-987 (joint)
Maredudd ab Owain | 987-999
Cynan ap Hywel | 999-1005
Edwin ab Einion | 1005-1018
Cadell ab Einion | 1005-1018
Llywelyn ap Seisyll | 1018-1023
Rhydderch ab Iestyn | 1023-1033
Hywel ab Edwin | 1033-1044
Gruffydd ap Llywelyn | 1044-1047
Gruffydd ab Rhydderch | 1047-1055
Gruffydd ap Llywelyn | 1055-1063
Maredudd ab Owain | 1063-1072
Rhys ab Owain | 1072-1078
Rhys ap Tewdwr | 1078-1093
Under English rule | 1093-1135
PRINCES OF DEHEUBARTH
Gruffydd ap Rhys | 1135-1137
Anarawd ap Gruffydd | 1137-1143
Cadell ap Gruffydd | 1143-1153
Maredudd ap Gruffydd | 1153-1155
Rhys, Lord Rhys ap Gruffydd | 1155-1197
Gruffydd ap Rhys | 1197-1201
After the year 1201, the descendants of Gruffydd ap Rhys ruled as Lords of the Cantref Mawr only.
Under the rule of Hywel Dda and his successors, Deheubarth expanded its influence and control over other Welsh territories. At its height, the kingdom encompassed a significant portion of southern Wales, extending from Pembrokeshire to the Gower Peninsula and parts of Ceredigion (Ceredigyawn) and Carmarthenshire. Like other Welsh kingdoms, Deheubarth faced internal conflicts and external threats from neighboring kingdoms and Anglo-Norman forces. The kingdom went through periods of fragmentation and reunification under different rulers.
During the twelfth century, the Normans, who had conquered much of England, launched campaigns into Wales. Deheubarth faced Norman incursions, and its last king, Rhys ap Gruffydd (known as Lord Rhys), struggled to maintain autonomy against Norman advances.
By the late twelfth century, Deheubarth was effectively integrated into the emerging Principality of Wales, under the rule of the English crown. This marked the end of its existence as an independent kingdom.
Source
Kings and Princes of Deheubarth | David Nash Ford’s Early British Kingdoms