In the early 1770s the Mundurucu raided Portuguese settlements along the Amazon. In response, the governor of Pará sent a military expedition against them in 1775. The expedition, armed with guns, soundly defeated the Mundurucu, who fought with bows and arrows. Afterward, the Portuguese recruited Mundurucu men to serve as mercenaries against other Indian groups in the region. The alliance gave the Mundurucu access to metal tools and other manufactured goods, which they received in exchange for military service. By the late 1800s the region's Indian groups were under Brazilian control and mercenaries were no longer needed. Instead, world demand for rubber tires brought rubber tappers to the Tapajós River Basin, where wild rubber trees ( Havea brasiliensis ) grew in abundance. The tappers traded goods to the Mundurucu in exchange for manioc flour. The Mundurucu learned to tap and cure rubber latex and became part of the patronage system that controlled the rubber trade. During the mid-1950s, prospectors discovered gold north of the reservation. Miners bought manioc flour and hired young Mundurucu men to dig alluvium from creeks. The sediment was run through sluices and panned for gold dust. These young men returned to the reservation and began to mine placer deposits, a more lucrative activity than rubber tapping.
The Mundurucu have some contacts with other Indian groups. A few Apiaca and Kayabi live among them. To the east live the Kayapo, whom the Mundurucu regard as enemies. Four Indian posts are located within the reservation, and its administrative center and a clinic are near the town of Itaituba. These are staffed by the Ministry of Interior's National Indian Foundation (Fundação Nacional do Índio, FUNAI). Contacts with Brazilian peasants, riverboat traders, FUNAI staff, and Roman Catholic and Protestant missionaries from Germany, the United States, and Switzerland have influenced Mundurucu culture and society.