Priteni is the source of the Welsh language word Prydain , Britain . This has the same source as the Goidelic word - the Cruithne called the early Brythonic-speaking people of Ireland and the north of Scotland . Priteni is the source of the Welsh language term Prydain , Britain , which has the same source as the Goidelic term Cruithne used to refer to the early Brythonic-speaking inhabitants of Ireland and the north of Scotland .