William the Conqueror commissioned the Domesday Book after his conquest of England in 1066. Its survey, completed in 1086, gave an overview of population and a breakdown of which lands were leased to whom as tenants under the new feudal system. It also contained information about what taxable sources of income each area supported, although large areas were missed out. This information was important for the new Norman crown because of the extent to which the existing Anglo-Saxon/Danish-derived social hierarchy of England had been removed and replaced with Normans. William installed his own supporters as land-owning nobility and enforced a feudal hierarchy under which all land was owned by the king and leased to nobility, successively down to the peasant classes. The information in the census shows how the population was evenly and sparsely spread over the country as people inhabited small villages and farms from which they could work the land.