How did fish runs and cultivation affect settlements in the eastern Gran Chaco?

In the eastern Gran Chaco, the presence of seasonal fish runs in larger rivers and the practice of relatively productive cultivation significantly influenced settlement patterns. Unlike the nomadic groups in the drier western regions—who were forced to shift camps frequently as water holes dried up—these environmental and agricultural factors allowed the indigenous peoples of the eastern Chaco to maintain larger, more stable, and less mobile settlements.1

However, this dynamic shifted following the introduction of the horse by the Spanish. Many groups, such as the Caduveo and other Guaycuruan-speaking peoples, abandoned their limited horticulture to become predatory nomads. These groups transitioned into raiding Spanish settlements for cattle and capturing slaves from more sedentary tribes, though they often maintained base settlements with permanent houses to keep their livestock and captives. Other tribes, including the Abipón, Mocoví, and Lengua, also adopted a mobile lifestyle centered on horse and cattle herding.21