King of Wales was a very rarely used title, because
Wales never achieved the degree of political unity that
England or
Scotland did during the
middle ages. While many leaders in Wales called themselves king, the country was only truly united under the rule of one man from 1055–1063....
From the smaller kingdoms of Wales eventually emerged four major powers: Powys, Gwynedd, Dyfed/Deheubarth and Morgannwg. With Wales now developing into a more consolidated entity, it ultimately set the stage for Gruffudd ap Llywelyn in the mid-11th century. Alliances with Anglo-Saxon dynasties and Vikings helped him unite the country, and even conquer land belonging to the English. "In 1055 he absorbed
Deheubarth as well, thus becoming in effect King of Wales".
[2] John Davies states that Gruffydd was "the only Welsh king ever to rule over the entire territory of Wales... Thus, from about 1057 until his death in 1063, the whole of Wales recognised the kingship of Gruffudd ap Llywelyn. For about seven brief years, Wales was one, under one ruler, a feat with neither precedent nor successor."
[3] After his betrayal and death at the hands of his own men, Wales fell into civil war from other leaders seeking to fill the void of power and become king.
Gruffydd ap Llywelyn was, however,
not referred to as King of Wales at the time, but rather as "
King of the Britons". He was the last of a long line of paramount rulers among the insular Britons to have this title bestowed upon him, and possibly the only one to truly rule over all the (independent) Britons. For by this time, if not earlier, Wales was the only part of Britain remaining under
Brittonic rule.
[3]