633. The diocese stretched from Ferrol to the Eo River. In Spain, the area has sometimes been dubbed "the third Britain" or "the last Britain". Non-Anglo-Saxon kingdoms began appearing in western Britain, and are first referred to in Gildas' De Excidio. To an extent these kingdoms may have derived from Roman structures. But it is also clear that they drew on a strong influence from Hibernia, which was never part of the Roman Empire. Archaeology has helped further the study of these kingdoms, notably at sites like Tintagel or the hillfort at South Cadbury. In the north there developed the British kingdoms of the Hen Ogledd, the "Old North", comprising Ebrauc (probable name), Bryneich, Rheged, Strathclyde, Elmet and Gododdin. 5th- and 6th-century repairs along Hadrian's Wall have been uncovered, and at Whithorn in south western Scotland (possibly the site of Ninian's monastery). Chance discoveries have helped document the continuing urban occupation of some Roman towns such as Wroxeter and Caerwent. Continued urban use might be associated with an ecclesiastical structure. Western Britain has attracted those archaeologists who wish to place King Arthur as a historical figure. Though there is little contemporary written evidence for this, archaeological evidence does suggest that a Romano-British king might have wielded considerable power during the sub-Roman period, as demonstrated by the creation of sites such as Tintagel and earthworks such as the Wansdyke. Such interpretations continue to attract the popular imagination and the scepticism of academics. While pushed back politically and linguistically, British scholars and ecclesiastics had a significant impact on the Anglo-Saxon newcomers through literacy, ecclesiastical social constructs and historical memory of the Roman period in Britain, particularly after the Christianizing of the Anglo-Saxons. Coming from a fully oral cultural background, the Anglo-Saxons were heavily influenced by the more developed Christianized and literate culture of the Britons. British scholars were often employed at Anglo-Saxon courts to assist in the management of the kingdoms. This reintroduced British culture to those parts of Britain lost to the British politically. The epitome of this process is the adoption of the legendary British war leader, King Arthur, as the national hero of the English, due to the literary work of Welsh historians. Environmental change effects There is evidence for climate change in the 5th century, with conditions turning cooler and wetter. This shortened the growing season and made uplands unsuited to growing grain. Dendrochronology reveals a particular climatic