The plateau is inhabited by the Asháninka or Ashéninka people along with late-twentieth century immigrants largely from the Andes mountains of Peru.

[1] The Gran Pajonal was named by the Spanish because, in a region of tropical rain forest, it features patches of small grasslands amounting to about 4 percent of its total area.

The Pajonal has no definite boundaries, but lies east of the Cerro de la Sal (Salt Mountain) area and is an outlier of the Andes.

The natural vegetation is tropical rain forest except for the anthropogenic grasslands, totaling about 9,700 hectares (24,000 acres) and deriving from hundreds or thousands of years of cultivation by the indigenous people.

The area was immediately attractive to both missionaries and settlers due to its relatively dense population of indigenous people and more salubrious climate than the Amazon lowlands.

Following the common Spanish strategy of reductions, the Franciscans began to force the indigenous people to live in communities adjacent to the missions rather than dispersed in small groups as was their custom.

The rebellion of Juan Santos Atahualpa, beginning in 1742, destroyed the missionary enterprise and left the Gran Pajonal in Asháninka control for 150 years although they suffered from periodic epidemics of European diseases and in the late 19th century from slave raids by businesses engaged in the gathering of rubber.

[8] In 1965, another religious organization, the Wycliffe Translators began work in the Pajonal and the majority of the missionaries became Protestants rather than Roman Catholics.

In the 1980s, with assistance from the World Bank and Denmark, the Asháninka achieved legal title to land belonging to 36 communities in the Gran Pajonal.