North, D. C., & Thomas, R. P. (1973). Part two, 900-1500. The rise of the West: A new economic history. pp. 19-89. In the early Middle Ages, the economy of Europe was based on a manoral system. In that system, a lord provided protection to a serf, who in turn provided free labor to the lord. This system began to undergo change during the High Middle Ages of the tenth through twelfth centuries. During that period, economic conditions in Europe changed with the "development and extension of a market for goods