By 1071 the last native-led rebellion against Norman authority in Yorkshire had been suppressed, and most of the leading Anglo-Scandinavian thanes in the region who had resisted William the Conqueror and his followers were either dead, in prison or in exile. Any intentions the Conqueror may have entertained of working with the Anglo-Scandinavian aristocracy on anything like a position of equality had been cast away. Over the next fifteen years nearly all of the families belonging to this aristocracy were either deprived of their lands or reduced to the level of subtenants. Domesday Book in 1086 records that twenty-five continental magnates introduced into Yorkshire by the Conqueror were in possession of over 90 per cent of the county's manors. A very large number of these manors appear to have been underdeveloped. If the Domesday figures are totalled and tabulated they suggest that, taken as a whole, agricultural land in Yorkshire had suffered a dramatic decline in value in the twenty years following the arrival of the Normans (Table 1). Much of the county was apparently characterised by low population and plough-team densities. Many estates were described as waste, and recorded without resources or value. In several areas the survey provides almost no information beyond tax assessment figures. In only a few had estates apparently weathered the twenty years of Norman rule well. All this begs a number of questions concerning what happened in Yorkshire between 1071 and 1086.