 In the first of many expeditions exploring the Piedras River, Father Pío Aza lead a group in 1911 to locate local indigenous groups and settle them in Christian missions.The Masco-Piro and Amahuaca were exploited and enslaved by rubber barons starting during the rubber boom.The rubber boom arrived in the Las Piedras in 1894 after large concentrations of high-quality rubber were found.