St. Samson was a generation younger than Illtud and was ordained by him at the abbey of Llanwit Major (Llanilltud Fawr). Illtud’s father was Bicanus, prince of Llydaw and his mother was Rieingulid, daughter of Anblawd, that is Amlawdd Wledig. V. Samsonis, tells that Illtud was a disciple of St. Germanus but chronology indicates this could not have been the bishop of Auxerre. The V. Ninnochae states:
“Sanctus Germanus episcopus ex Hibernensium regione transmissus a Sancto Patricio archiepiscopo, venit ad Brochanum regem Britanniæ.”[1]
It is likely that it was this Germanus who ordained Illtud. He was St. Garmon who, as indicated by Bartrum, was the Germanus of the Historia Brittonum. V. Samsonis is the oldest surviving Vita of the British saints and was written by a Breton who had direct knowledge of Illtud’s life from a deacon who had recieved the information from his uncle, Henoc. The latter indivdiual had himself obtained the material from his aunt, Anna of Gwent, the mother of the saint. This document makes it clear that Illtud was from Letavia in Wales, not Brittany. There are several indicators pointing to this being a region of Brycheiniog.
As evidence that Llydaw, in this context, is likely to have referred to a region of Brycheiniog, Parri produced the following map that shows the distribution of dedications to the family of Emyr Llydaw.[2] It demonstrates that the areas evangelised, supposedly by Bretons, covers most of Wales except Brycheiniog and surrounding areas which were, therefore, the location of their origin.

Dedications to the family of Emyr Llydaw and Ithel Hael, Parri, B., © Brecknock Society & Museum Friends.
[1] Baring-Gould, S., Fisher, J., 1911, 68.
[2] Parri, B., 2009, 133.