With the manorial side of serfdom in its connection with the widely prevalent open field system we have already attempted to deal in a former volume. That there may have been some continuity and continuance of estates managed on the Roman system can hardly be denied. However far the policy of extermination of the old inhabitants was carried, it never extended over the whole area. And the whole of Britain was not conquered in the same century. Even if the continuity of estates in Britain should be considered to have been entirely broken by the Anglo-Saxon invasions (which is hardly conceivable), it must be admitted that continuity and likeness between England and the Continent as to land management was very soon restored on monastic and other ecclesiastical estates, and perhaps also upon what was Royal domain. Nor can it be doubted that herein was a force greatly strengthening the manorial element. [Sidenote: Tribal custom only would not meet the whole case.] If we limit our view to the tribal side only of the problem, we recognise that in Scandinavia and in the Cymric districts of our own island and in Ireland tribal principles working alone tended powerfully, without help from the Roman side, to produce a class of tenants becoming _adscripti glebæ_ after four generations of occupation, but it did not produce either in Norway or in Wales or Ireland or in Celtic Scotland that general and typical form of occupation in uniform yardlands or ‘huben’ so prevalent in England and Germany on manorial estates with ostensibly single succession and services in so many points resembling those of the Roman colonate. Whether the manor was the indirect or direct successor of the Roman Villa--_i.e._ whether the continuity was broken or not--the _manorial_ use of the open-field system of agriculture seems to be required to produce the uniformity of holdings in yardlands and the single succession which marked what is roughly called the serfdom of the manorial estate. [Sidenote: The open-field system not of manorial origin.]