The founder of the III. Royal Tribe of Wales is listed as Bleddyn ap Cynfyn, King of Powys, A.D. 1046. In Burke he is given as "...derived from Mervyn, King of Powys, third son of Rhodri Mawr". The arms are given:
"Ar. a lion ramp. sa"
This again is a lion standing erect on the hind legs which would be silver in color. The shield would be black in color.
Meredith ap Bleddyn (son of Bleddyn ap Cynfyn) is given as "Prince of Powys".
Madoc, a son of Meredith ap Bleddyn, is given as "Prince of Powys-Fadog".
From: Burke, p. lxii, 1884 edition.