[2] Although their demographic dominance of the region has been reduced by European colonisation and the commensurate rise of mestizos, there are contemporary Guarani populations in Paraguay and parts of Argentina and Bolivia.

According to the Jesuit missionary Martin Dobrizhoffer, they practiced cannibalism at one point, perhaps as a funerary ritual, but later disposed of the dead in large jars placed inverted on the ground.

The first governor of the Spanish territory of Guayrá initiated a policy of intermarriage between European men and indigenous women; the descendants of these matches characterize the Paraguayan nation today.

In the early period, the name Paraguay was loosely used to designate the entire river basin, including parts of what are now Uruguay, Argentina, Bolivia, and Brazil.

[10] The Jesuit provincial Torres arrived in 1607, and "immediately placed himself at the head of those who had opposed the cruelties at all times exercised over the natives".

Originally a rendezvous place for Portuguese and Dutch pirates, it later became a refuge for criminals, who mixed with Native American and African women and actively participated in the capturing and selling of Guaranis as slaves.

The Jesuit priest Father Ruiz de Montoya discussed the difficulties of spreading the missions and his interactions with the Guarani in his book The Spiritual Conquest.

Ruiz de Montoya wrote that one of the Guarani caciques Miguel Artiguaye initially refused to join the missions until threatened by another Indigenous group.

[16] In 1629, an army of Paulistas surrounded the San Antonio mission, set fire to the church and other buildings, killed those who resisted or were too young or too old to travel, and carried the rest into slavery.

Within two years, all but two of the establishments were destroyed, and 60,000 Christian converts were carried off for sale to São Paulo and Rio de Janeiro.

Father Antonio Ruiz de Montoya purchased 10,000 cattle, and was able to convert the natives from farmers to stock raisers.

In the same year Father Montoya, after having successfully opposed the attempts of the governor and the bishop of Asunción to reduce the natives' liberties and the mission administration, sailed for Europe.

On this trip he was successful in obtaining letters from Pope Urban VIII forbidding the enslavement of the missionaries under the severest church penalties, and from King Philip IV of Spain, permitting Guaranis to carry firearms for defense and to be trained in their use by veteran soldiers who had become Jesuits.

When the next Paulista army, 800 strong, attacked the missions in 1641 they were met by a body of Christian Guarani armed with guns on the Acaray River.

Fearing the outcome of this decision, viceroy Antonio María Bucareli y Ursúa entrusted the execution of the mandate in 1768 to two officers with a force of 500 troops.

Guarani caciques from Mission San Luis wrote a letter to the Governor of Buenos Aires on February 28, 1768, to ask for the Jesuits to stay.

The missions were turned over to priests of other orders, chiefly Franciscans, but under a code of regulations drawn up by the viceroy and modeled largely on the Jesuit system.

According to the official census of 1801, fewer than 45,000 Guaranis remained; cattle, sheep, and horses had disappeared; the fields and orchards were overgrown or cut down, and the churches were in ruins.

A 2018 study in The Quarterly Journal of Economics found that "in areas of former Jesuit presence—within the Guarani area—educational attainment was higher and remains so (by 10–15%) 250 years later.

The enduring effects observed are consistent with transmission mechanisms of structural transformation, occupational specialization, and technology adoption in agriculture.

The Chririguanos were not finally pacified until the defeat in 1892 of forces led by their messianic leader Apiaguaiki Tumpa in the Battle of Kuruyuki.

[20] A group formed by members of the Guarani community called "Los Rumberos," or “The Patrollers,” safeguard the forest to deter further encroachment.

This region reaches nearly as far north as Santa Cruz de la Sierra and includes portions of the Guapay, Parapetí, and Ɨtɨka Guasu (or Pilcomayo) River valleys.