After four generations of peaceful rule, Princess Ceindrych's father, King Rhiwallon ap Idwallon, became the last male-line descendant of King Brychan to rule in Brycheiniog. His daughter and heiress married firstly her cousin, Prince Elisedd ap Ysgorda, in an attempt to keep the throne within the same dynasty. Unfortunately, their union was short-lived and, in the mid-7th century, Princess Ceindrych married a more distant relative from a younger branch of the House of Allmuir, King Cloten of Dyfed. Thus Dyfed and Brycheiniog became a United Kingdom.