Llanos Y Valdez / Llanos Y Valdes information?

So after a long grace period away from this, I decided to run a search and see what comes up and I found 2 things of promise. Problem is, they are very vague mentions in the posts that came up.

Does anyone know much of the surname Llanos Y Valdez(also spelt Llanos Y Valdes) and its connection to the surname Rivas? If there is information on the family itself in terms of a history, thats what I'd prefer to know. It was mentioned they are "old families", so, I'm guessing there is a lot behind these.

Thanks Primos..