With reference to the Arthur series and the legend of Sagramor, you may be interested in this site which tells of a unit of Roman Auxillaries from modern day Morroco statoned at Hadrians wall at Aballava, modern day Burgh-by-Sands with evidence that some married, had children and stayed behind in Britian although DNA has been diluted too much to find. http://www.bbc.co.uk/tyne/roots/2003/10/blackhistoryromans.shtml. Peter Brown