The Old World had known of the fabulous riches of Mexican and Peruvian mines for well over a century when reports began to come in of the wealth of the Buenos Aires pampas. Acarete du Biscay and Antonio de Ulloa were among those astounded by the abundant herds of wild cattle to be found on those endless plains and the latter's writings provided Adam Smith with examples of a primitive economy.1 By the time The Wealth of Nations was published, however, that early primitiveness was changing. According to Cosme Bueno, the increasing demand for hides for export had brought about a decline in the number of cattle around Buenos Aires with the result that simple hunting had become cattle raising.2 The supply of meat to the city had always necessitated cattle raising, but the ever-erratic demand for export hides had to be met by hunting expeditions - the vaquerías. No new hunting licences were granted after 1720 and the first surprise attacks a few years later by Pampa indians looking for domestic cattle signalled the end of the wild herds.3 The intensification of foreign demand for hides led in the first place to the spread of the vaquerías into Entre Ríos and the Banda Oriental and, later on, particularly after the adoption of free-trade policies by post-revolutionary governments, to the proliferation of estancias on the Buenos Aires pampas.