Rhein, Kings of Dyfed & Brycheioniog
Rhein was the son of Cadwgan ap Caten ap Cloten. He appears to have inherited Dyfed and most of Brycheiniog from his father, though part the latter Kingdom passed to Aust, probably his brother. It was during King Rhein's mid-8th century rule, that Dyfed was invaded by Seisyll, King of Ceredigion. The Cerediganians conquered Ystrad Towy, and Rhein's dual kingdom was split in two. Both areas appear to have been known for a time as Rheinwg after their King.