The economy of England in the Middle Ages, from the Norman invasion in 1066, to the death of Henry VII in 1509, was fundamentally agricultural, though even before the invasion the market economy was important to producers. Norman institutions, including serfdom, were superimposed on an existing system of open fields and mature, well-established towns involved in international trade. Over the next five centuries the economy would at first grow and then suffer an acute crisis, resulting in significant political and economic change. Despite economic dislocation in urban and extraction economies, including shifts in the holders of wealth and the location of these economies, the economic output of towns and mines developed and intensified over the period. By the end of the period, England had a weak government, by later standards, overseeing an economy dominated by rented farms controlled by gentry, and a thriving community of indigenous English merchants and corporations.