Now a remote economic backwater, just over a hundred years ago Bolivia’s northern Amazon frontier was one of the most commercially desirable stretches of territory on earth. The region supports some of the richest natural rubber forests in the whole of the Amazon, and in the late nineteenth century a surge in international demand for rubber generated an unprecedented economic boom. Great fortunes were made by the so-called “rubber barons” who controlled production, but for the indigenous peoples of the Amazon the rubber boom was an unmitigated disaster. They were recruited by force to work collecting wild rubber under conditions of appalling brutality, and their population declined catastrophically. Little of the money made was reinvested, and when the boom ended in the early twentieth century with the establishment of rubber plantations in Asia, the region – and its main towns, agreeable Riberalta and Brazilian flavoured Guayaramerín – slipped back into the economic torpor which characterizes it today, with collection of wild Brazil nuts (known as castañas) the main export industry. To the north of Guayaramerín, the small and sleepy town of Cachuela Esperanza provides an atmospheric insight into the days of the rubber boom.