 North Wales has had human settlements since prehistoric times . By the time the Romans reached Britain , the area that is now Clwyd was occupied by the Celtic Deceangli tribe . They lived in a chain of hill forts running through the Clwydian Range and their tribal capital was <unk> at an important river crossing on the River Conwy . This fell to the Romans , who built their own fort here , in about 75 AD and the whole of Wales was soon under their control . After the Roman departure from Britain in 410 AD , the successor states of Gwynedd and Powys controlled what is now Clwyd . From about 800 onwards , a series of dynastic marriages led to Rhodri Mawr inheriting the kingdoms of Gwynedd and Powys . After his death , this kingdom was divided among his three sons and further strife followed , with not only Welsh battles being fought , but also many raids by Danes and Saxons . 
