The gravel bank north of the ford, by which what is presumed to have been the drovers' road from south to north crossed the river, had supported a very considerable population, and had attained a very considerable civil importance, long before the Conquest. It is difficult to believe that any new, especially that any extensive, centres of population grew up in Anglo-Saxon Britain, upon sites chosen by the barbarians. The Romans had colonised and densely populated every suitable spot. The ships' crews of open pirate vessels had no qualities suitable to the founding of a town; and when there is no direct evidence it is always safer of the two conjectures in English topography to believe that any spot which we find inhabited and flourishing in the Anglo-Saxon period, even at its close, was not a town developed during the Dark Ages but one which the pirates, when they first entered the island, had found already inhabited and flourishing, though sometimes perhaps more British than Roman. But though this is always the more historical way of looking at the probable origin of an English town it must be admitted that there is no direct evidence of any town upon the site of Oxford before the Danish invasions, and the first mention of the place by name is as late as eleven years after Alfred's death, when it is recorded that Edward, his son, "took possession of London and of Oxford and of all lands in obedience thereunto." This first mention, slight as it is, characterises Oxford as being the town of the upper Thames Valley at the opening of the tenth century, and we have what is usually a good basis for history--that is, ecclesiastical tradition and a monastic charter--to show us that a considerable monastery had existed upon the spot for a century and a half before this first mention in the Chronicle.