Oh, how wonderful!  Look at this link I just came across.  It has the history of Wales in a summarized version right through the run of years I'm looking at.  I've already scoured Wikipedia, but this runs through a nice brief timeline all on one page.
http://www.britannia.com/celtic/wales/timeline/tl03.html

I still can't decide exactly when "she" would have been born but "the name Aranwen Ridhelic is a spelling appropriate for around 1200. The byname comes from 1194, when it appears in Geraldus Cambrensis' Descriptio Cambriae as Ridhelic."

The first Eisteddfod was held in 1176. Was she perhaps a youth at this time? Or maybe she was born in that year.  I was born in 1976 so I fancy this '76 year a bit. 

Isn't this bit quite fascinating?
"According to a popular Welsh legend, Prince Madog of Gwynedd, accompanied by a group of followers, made landfall on what is now Mobile Bay, Alabama some time in 1169."