of internal strife. It also lost the state of Acre, in the Acre War; important because this region was known for its production of rubber. Peasants and the Bolivian army fought briefly but after a few victories, and facing the prospect of a total war against Brazil, it was forced to sign the Treaty of Petrópolis in 1903, in which Bolivia lost this rich territory. Popular myth has it that Bolivian president Mariano Melgarejo (1864–71) traded the land for what he called "a magnificent white horse" and Acre was subsequently flooded by Brazilians which ultimately led to confrontation and fear of war with Brazil.
In the late 19th century, an increase in the world price of gold brought Bolivia relative prosperity and political stability. During the early 20th century, tin replaced gold as the country's most important source of wealth. A succession of governments controlled by the economic and social elite followed laissez-faire capitalist policies through the first thirty years of the 20th century.
Living conditions of the native people, who constitute most of the population, remained deplorable. With work opportunities limited to primitive conditions in the mines and in large estates having nearly feudal status, they had no access to education, economic opportunity, and political participation. Bolivia's defeat by Paraguay in the Chaco War (1932–35), where Bolivia lost a great part of the Gran Chaco region in dispute, marked a turning-point.
Nationalist Revolutionary Movement
The Revolutionary Nationalist Movement (MNR) The most historic political party, emerged as a broadly based party. Denied its victory in the 1951 presidential elections, the MNR led a successful revolution in 1952. Under President Víctor Paz Estenssoro, the MNR, having strong popular pressure, introduced universal suffrage into his political platform and carried out a sweeping land-reform promoting rural education and nationalization of the country's largest
