The House of Gwynedd is divided between the earlier House of Cunedda, which lasted from c.420-825, and the later House of Aberffraw, beginning in 844. The first is so named after Cunedda, the founding king of Gwynedd; and the second after Aberffraw, the old capital of Gwynedd.
Under the laws of Hywel Dda, which were adapted from the much earlier pagan Molmutine Laws, any son can inherit from his father. This refers even to illegitimate sons if they are acknowledged by their father. The throne cannot be inherited through the female line unless both her father and the ancestry of her spouse were royal. In many examples cousins were inter-married, which made the distinction somewhat academic.
The House of Aberffraw began with the accession of Rhodri Mawr to the throne of Gwynedd. His father Merfyn Frych ap Gwriad had seized the throne of Gwynedd on the death of the last of the old royal line Hywel ap Rhodri Molwynog. He had married the former king's niece Ethyllt verch Cynan ap Rhodri Molwynog and their son, thus uniting both lines, was Rhodri Mawr.
The plot was carried out (by a Scot) in 1378, and Saint Leger on the banks of the Garonne (opposite Chateau Calon Segur - not a Welsh name, alas) became the burial place of the last of the male line of the house of Aberffraw.Following the extinction of that line,...