The princes of Powys Fadog would build their royal seat at Castell Dinas Brân, and their religious center at Valle Crucis Abbey.

[1][2] He was a member of the Royal House of Mathrafal, founded by grandfather, King Bleddyn ap Cynfyn, who led a defence with the Anglo-Saxons against William the Conqueror.

[2][1] Madog would lost for a time the Lordship of Yale when he allied himself with Ranulf de Gernon, 4th Earl of Chester, against King Owain Gwynedd.

[3] Gruffydd received the cantref of Maelor and the commote of Yale (Iâl) as his portion, and later added Nanheudwy, Cynllaith, Glyndyfrdwy and Mochnant Is Rhaeadr.

[4][3] This northern realm became known as Powys Fadog after the accession in 1191 of his son prince Madog ap Gruffudd, who reigned until 1236, and after whom it may be named (see alternative translations above).

[7] When Gruffydd died in 1269, his eldest son prince Madog II succeeded to the throne, but the small portion of the realm awarded to his younger brothers caused rebellion, in which England became engaged.

It appears that prince Madog II (or at least men loyal to him) remained at Dinas Brân for some time after this accord, because Henry de Lacy, Earl of Lincoln commanded an English force to take the castle on 10 May 1277.

Gruffydd Fychan (the brother of Madog II and last heir to the throne of Powys Fadog) was pardoned but reduced in status to a minor local noble or uchelwr.