Because it was less accessible by major rivers, the department of Madre de Dios was among later ones to be explored during the late-19th-century rubber boom in the Amazonian Basin. Rubber barons active in the department included Peruvian Carlos Fermín Fitzcarrald of Iquitos, as well as Brazilian and Bolivian interests. The workers for tapping rubber brought in endemic European diseases, causing epidemics and high fatalities among the indigenous peoples along the Manu River from 1889 to 1892, as they had never been exposed to these diseases before. Another epidemic occurred in 1896.