With the election of Evo Morales and his party “Movement to Socialism” (MAS) in 2005, Bolivia has become famous as Latin America’s only country with an indigenous party in power. It is misleading, however, to refer to an “indigenous government” representing all of Bolivia’s ethnic diversity. Instead, one can identify two subgroups amongst Bolivia’s indigenous population: indigenous peoples from the Andean highlands and valleys (“tierras altas” or “occidente”) and indigenous peoples from the eastern and Amazonian lowlands (“tierras bajas” or “oriente”). Research has so far focused on the Andean indigenous peoples or treated the indigenous population as uniform. It has placed its main focus on parties and not on voters. This paper aims at differentiating the picture. It sets out to show that highland and lowland indigenous peoples have voted very differently before MAS came to power and especially since then. While the indigenous peoples from the highlands have mostly voted for parties of the left political spectrum, the lowland indigenous peoples have spread their votes on a large number of parties. The paper attempts to answer the question of how these differences in the voting behaviour of Bolivia’s indigenous peoples can be explained. It follows the hypothesis that historical relationships between indigenous peoples and political parties have a strong impact on the diverging voting behaviour of the country’s indigenous peoples. Ethnic voting is analysed in the time span from 1985 until 2014 within a mixed-methods design, interpreting municipality level census and election data in their historical context, complemented by guided interviews with social scientists, indigenous politicians and activists.