At the time of the arrival of the Spaniards in the latter part of the sixteenth century, the Chaco was inhabited by the Toba and the linguistically related Pilagá, Mocoví, and Abipon, as well as by the Mataco and Vilela (later called Chunupí). Traditionally there was animosity among the Toba, Mocoví, and Abipon, although they later formed alliances for the purpose of attacking Spanish settlements. It took the Spaniards more than 300 years to conquer and colonize this region. Initially, they may not have been sufficiently interested in the forests and the semitropical swamps of the Chaco except as a means of access to the treasures of gold and silver that were purported to exist toward the northwest (the mythical city of the Césares, for example.) Thus, the Spaniards tried to consolidate roads rather than to dominate the territory. Also, once the Indians of the Chaco had begun to use horses it became very difficult to conquer them by force of arms. Projects were initiated in Tucumán, as well as in Asuncón and Corrientes, to establish encomiendas and cities, but there was no actual occupation of the Chaco until the end of the nineteenth century. The Jesuits, until their expulsion in 1767, founded some reductions as part of a program to contain and civilize the Chaco Indians. These, especially the Mocoví, Abipon, and Toba, conducted surprise attacks to steal goods (livestock, arms, and captives) from the cattle ranches and the villages of Santa Fe and Buenos Aires.
Beginning in 1870 the military tried to consolidate the Chaco territory and bring it under the control of the national government. This resulted in repeated fighting with the Toba and the Mocoví. After General Victorica's expedition in 1884, however, the Indians did not renew their armed struggle. Around that time settlers, lumber mills, and cattle ranching were introduced in Toba territory. The mills at Salta, Tucumán, Jujuy, and Chaco attracted the natives as temporary wage earners and brought about significant seasonal migration. The cities of Formosa and Resistencia were founded and became points of attraction for White settlers. Cotton became the monoculture that determined the area's economy, and the Toba and the Movocí came to be an exceptional labor force.
Agricultural economic activity, the pressures brought to bear by ranchers and provincial authorities, and hostility among the Toba and the Mocoví triggered confrontations with the police in Napalpí in 1924. The friction was caused by attempts to force the natives to work in settlements where they had been congregated in reductions, obliging them to refrain from roaming freely about the province. In 1947 in Las Lomitas (Formosa), Toba, and Pilagá natives faced off with the police when they congregated to join the indigenous leader of a nativistic religious movement. Furthermore, the Chaco War between Paraguay and Bolivia in 1933 modified the geopolitical map of the area. Toward the end of the nineteenth century, Anglican influence made itself felt in the northwestern part of Formosa and on the Saltenian side of the Pilcomayo. Franciscan missionaries arrived at the beginning of the twentieth century and founded missions in the eastern part of Formosa. The sedentary and secular influences of these missions are evident in many of the settlements that have persisted, for example at the La Paz Mission (Anglican) and the Tacaaglé and Laishí missions (Franciscan). The wave of evangelical missions of the 1940s was a key factor in the appearance of syncretic indigenous religious organizations, like the Toba United Evangelical Church, which was organized at the beginning of 1960 in Chaco Province.