I am trying to find out more in depth material on Rhodri Mawr. (Rhodri ap Merfyn)
(844-878) King of Gwynedd.

In the tenth century Rhodri's grandson, Hywel ap Cadell (Hywel Dda~"the good" c.920-950) united Seisyllwg in Deuheubarth with Gwynedd.

Right now, all I am finding on the net and in books I have are references to Rhodri Mawr, and the very basic facts.
I wanted to go more in depth in order to look into the beginnings of Wales as a Nation.
Also, hoping to present this tale and the themes to a class I am in, but with lack of really juicy information, that say everyone wouldn't learn as a kid at school here; I may have to choose another theme.

Why is it so difficult to find information on the post-roman era?
(used to be called the dark ages).
I live in Whitland which was Hywel Dda's base. It's easy to get books on the laws. But not much else.
Or the period just before Hywel Dda. There is so much celebrating over the laws being codified.
I suppose that alone should tell me a lot!

Does anyone have any suggestions where to look?
Thanks.

Ylais