 The 5th century saw the withdrawal of Imperial Roman support from Britain , and the succeeding centuries , the Dark Ages , witnessed the emergence of a national identity and of kingdoms . The area which would become the Rhondda lay within Glywysing , an area that incorporated the modern area of Glamorgan , ruled by a dynasty founded by <unk> . This dynasty was later replaced by another founded by Meurig ap Tewdrig whose descendant Morgan ap Owain would give Glamorgan its Welsh name Morgannwg . With the coming of the Norman overlords after the 1066 Battle of Hastings , south @-@ east Wales was divided into five <unk> . The Rhondda lay within Penychen , a narrow strip running between modern day Glyn Neath and the coast between Cardiff and <unk> . Each cantref was further divided into commotes , with Penychen made up of five such commotes , one being Glynrhondda . 
