There is some general agreement among scholars about the conditions under which slavery has existed, particularly in large-scale slave societies as in the ones in the Americas. In the analysis of such slave societies, economic surpluses play a major role, and variants of the Domar–Nieboer argument that related slavery to a high ratio of land to labour have been frequently resorted to. If some scepticism about this argument exists today, certainly it was one often used by many contemporaries in describing the rise and fall of slavery and the new forms of labour control that replaced it. Correspondingly, discussions of the expected ending of slavery were frequently based on arguments positing a declining ratio of land to labour. Expectations of the reported successes (or lack of them) of the transition to free labour were also related to the relative amounts of land and labour. The rise and fall of smaller-scale slave societies was often explained by economic elements, although various social and political factors may have had a major influence in some of these cases. Slavery, in those societies with written documents, was generally dealt with through extensive law codes, often with thorough details and broad coverage. These laws provided the fundamental basis for the control of slave labourers, as well as imposing limits on the masters and non-slaveholding free people.