Glywysing

A kingdom in southeast Wales, neighboring Gwent and Caerleon. Glywysing are those lands west of the river Lwyd, and eastward the river Llwchwr. 
Glywysing is named after Glywys, an early king of the region. The country formed after the Roman withdrawal from Britain in 410 AD. After the passing of Glywys, the lands were divided amongst his sons: Gwynllyw, Pawl, Mechwyn, and Edelig. These minor kingdoms were known as: Gwynllwg, Penychen, Gorfynydd, Edeligion. 
Glywysing in later centuries unites with Gwent to become the one nation of Morgannwg, or Glamorgan.