Thats obviously not true. I have no idea where you got that from, please give a source. (Especially for the Tiber being a Breton)
The Arcturian Heresy
http://uesp.net/wiki/Skyrim:The_Arcturian_Heresy
the Ghost of old Hroldan
http://uesp.net/wiki/Skyrim:The_Ghost_of_Old_Hroldan
Michael Kirkbride's posts
http://www.imperial-library.info/content/forum-archives-michael-kirkbride
Lorkhan and his avatars:1. Wulfharth L
2. Hjalti O
3. Ysmir R
4. Talos K
5. Arctus H
6. Septim A
N
Tiber was a breton named Hjalti from high rock. He merged with the nord Ysmir Wulfharth, and Zurin Arctus to form Talos
TALOS IS LORKHAN, SON OF SITHIS, REBORN
As for the Nedes
http://www.imperial-library.info/content/forum-archives-others
On the origin of Nedes
The usual Imperial arrogance. The hoary old "Out of Atmora" theory has been widely discredited (no reputable archaeologist would publicly support it these days), but the Imperial Geographers continue to beat the drum of the Nordic Fatherland in the best tradition of the Septim Empire. They seem to think that the imprimature of officialdom gives their outdated scholarship added weight -- which, unfortunately, it appears to in the eyes of the ever-gullible public which continues to snap up the latest Pocket Guides along with the rest of their Imperial Certified pablum.
http://www.imperial-library.info/content/forum-archives-michael-kirkbride
Out of Atmora (07/10/08):And for the last time (uh huh), Nedes != Atmorans. That's just shoddy scholarship from a bygone regime.