Wales, Ireland and Scotland all exhibited a cultural, linguistic and social dualism between an anglicised and urbanised south and east and a Celtic-speaking, less populous north and west. In thirteenth century, the coastal plain of south Wales was controlled reasonably securely by the Anglo-Norman Marcher lords. In 1238 all the princes of Wales swore allegiance to Dafydd ap Llywelyn ap Iorwerth at Strata Florida and two years later Llywelyn, a man whose deeds it were difficult to relate, died. The aftermath of Llywelyn's death shows clearly how Welsh inheritance practices could lead to political instability. At the beginning of the thirteenth century it still seemed possible that the Anglo-Norman lords and settlers who acknowledged the authority of the king of England might attain political control of the whole of Ireland. The thirteenth-century kings of the Scots were continental rather than Celtic in the way they avoided the partible inheritance and segmentary competition of their contemporaries in Wales and Ireland.