Elystan Glodrydd (died c. 1010) was, according to Welsh genealogical tracts, the founder of the fifth Royal Tribe

Fifteen Tribes of Wales

The five royal tribes of Wales and The fifteen tribes of Gwynedd refer to a class of genealogical lists which were compiled by Welsh bards in the mid-15th century. These lists were constructed on the premise that many of the leading Welsh families of their time could trace their descent to the...

 of 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...

.

Very little is known about Elystan himself, but his descendants, including Cadwallon ap Madog

Cadwallon ap Madog

Cadwallon ap Madog was the son of Madog ab Idnerth who had died in 1140, while Idnerth was a grandson of Elystan Glodrydd who had died in around 1010 and had founded a dynasty in the Middle Marches of Wales, in the area known as Rhwng Gwy a Hafren .-Prince of Maelienydd:After the death of Madog ab...

, ruled a minor principality in mid Wales, part of Rhwng Gwy a Hafren

Rhwng Gwy a Hafren

Rhwng Gwy a Hafren was a region of medieval Wales, located in the Welsh Marches between Powys to the north and Brycheiniog to the south. It was bounded by the rivers Wye and Severn , hence its name. It covered approximately the same territory as Radnorshire, now part of the county of Powys...

 - the land between the Wye and the Severn. An early Welsh genealogical tract links him to Gwrtheyrnion

Gwrtheyrnion

Gwrtheyrnion or Gwerthrynion was a commote in medieval Wales, located in Mid Wales on the north side of the River Wye. For most of the Middle Ages its rulers operated independently of other powers, but it was sometimes associated with the cantref of Maelienydd and the Kingdom of Powys, and, in the...

, while other descendants ruled Maelienydd

Maelienydd

Maelienydd, sometimes spelt Maeliennydd, was a cantref and lordship in east central Wales covering the area from the River Teme to Radnor Forest and the area around Llandrindod Wells. The area, which is mainly upland, is now in Powys...

 and Elfael

Elfael

Elfael was one of a number of Welsh kingdoms occupying the region between the River Wye and river Severn, known as Rhwng Gwy a Hafren, in the early Middle Ages. Later in the Middle Ages it became a cantref. After the Laws in Wales Act of 1535, it became part of the new county of Radnorshire. ...

. Other descendants ruled Cedewain. These territories lay in an area roughly equivalent to the later counties of Radnorshire

Radnorshire

Radnorshire is one of thirteen historic and former administrative counties of Wales. It is represented by the Radnorshire area of Powys, which according to the 2001 census, had a population of 24,805...

 and southern Montgomeryshire

Montgomeryshire

Montgomeryshire, also known as Maldwyn is one of thirteen historic counties and a former administrative county of Wales. Montgomeryshire is still used as a vice-county for wildlife recording...

, in today's county of Powys

Powys

Powys is a local-government county and preserved county in Wales.-Geography:Powys covers the historic counties of Montgomeryshire and Radnorshire, most of Brecknockshire , and a small part of Denbighshire — an area of 5,179 km², making it the largest county in Wales by land area.It is...

. It has been conjectured by P.M. Remfry that these territories formed a polity known as Cynllibiwg

Cynllibiwg

Cynllibiwg was evidently a place name in early medieval Wales.The earliest surviving reference to it is in the Historia Brittonum, which describes a marvelous spring in the regione of Cinlipiuc that has an abundance of fish despite not being fed by a stream...

. However, this is not generally accepted.

A Welsh genealogical source makes Elystan the seventh in descent from Iorwerth Hirflawdd

Iorwerth Hirflawdd

Iorwerth Hirflawdd was an ancestor of various medieval rulers in mid Wales. His epithet means 'long trouble', but nothing is known of how he acquired it, nor otherwise of his life....

, who probably died in the mid 9th century.