thumb|Contemporary Guarani shaman In 1607, Spanish King Philip III sent a letter to the governor of Rio de Plata Hernandarias de Saavedra to instruct him to send the newly arrived Jesuits to begin their missionary work. With Spanish royal protection, the first Guayrá mission, Loreto, was established on the Paranapanema by Father Joseph Cataldino and Father Simon Macerata in 1610. 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. Artiguaye then returned to the mission and begged for protection. As the mission provided the only real possible protection against enslavement, the Guarani flocked there in such numbers that twelve more missions were created in rapid succession, containing all 40,000 Guaranis. The Jesuits were seen as intermediaries between the Spanish authorities and the Guarani caciques. The Jesuit missions needed new converts and required workers to assist in the maintenance of the missions. The Guarani helped grow the crops to sustain the missions' populations and also produce goods to sell and trade to fund the missions. Stimulated by this success, Father González and two companions journeyed to the east bank of the Uruguay River (now the country of Uruguay) and established two or three small missions in 1627. The local tribes killed the priests and the neophytes and burned the missions.
thumb|Contemporary Guarani shaman In 1607, Spanish King Philip III sent a letter to the governor of Rio de Plata Hernandarias de Saavedra to instruct him to send the newly arrived Jesuits to begin their missionary work. With Spanish royal protection, the first Guayrá mission, Loreto, was established on the Paranapanema by Father Joseph Cataldino and Father Simon Macerata in 1610. 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 Artiguaye then returned to the mission and begged for protection. As the mission provided the only real possible protection against enslavement, the Guarani flocked there in such numbers that twelve more missions were created in rapid succession containing all 40,000 Guaranis. The Jesuits were seen as intermediaries between the Spanish authorities and the Guarani caciques. The Jesuit missions needed new converts and required workers to assist in the maintenance of the missions. The Guarani helped grow the crops to sustain the missions' populations and also produce goods to sell and trade to fund the missions. Stimulated by this success, Father González and two companions journeyed to the east bank of the Uruguay River (now the country of Uruguay) and established two or three small missions in 1627. The local tribes killed the priests and the neophytes and burned the missions.