" Within a few decades after the conquests of Cortés and Pizarro, the cattle population of Spanish America doubled as rapidly as every fifteen months. From Mexico to the pampas of Argentina, the vast open spaces of the New World swarmed black with livestock. One French observer in Mexico wrote in wonderment at the "great, level plains, stretching endlessly and everywhere covered with an infinite number of cattle. "

― William J. Bernstein , A Splendid Exchange: How Trade Shaped the World from Prehistory to Today