Paraguayan Chaco

[citation needed] The Chaco region was the scene of the longest territorial war to occur in South America; an armed conflict between Paraguay and Bolivia, lasting from 1932 to 1935.

[citation needed] The Paraguayan Chaco is located between the Pilcomayo and Paraguay Rivers, which provide saline soils that attract a rich variety of plants and animals.

Larger animals present in the region include jaguar, ocelot, puma, tapir, giant armadillo, giant anteater, many species of foxes, numerous small wildcats, the agouti (a large rodent), the capybara (water hog), the maned wolf, the palustrian deer, peccaries, including the endemic Chacoan peccary, and the guanaco (the wild relative of the llama).

Eastern Chaco is noted for its park-like landscape of clustered trees and shrubs interspersed with tall, herbaceous savannahs.

To the west, a wide transition zone grades into the espinal, a dry forest of spiny, thorny shrubs and low trees.

One of the most impressive vegetation formations is called the quebrachales, which consists of vast, low hardwood forests where various species of quebracho trees are dominant.

In the more arid western Chaco, thorn forests, the continuity of which is occasionally broken by palm groves, saline steppes, and savannas, created by fire or deforestation, are dominated by another quebracho tree that has a lower tannin content and is used most often for lumber.

There is also a marked increase in the number and density of thorny species, among which the notorious vinal (Prosopis ruscifolia) was declared a national plague in Argentina because of how its thorns, up to a foot in length, posed a livestock hazard in the agricultural lands it invaded.

It also hosts the annual Trans Chaco Rally, a prominent automobile race, which is considered one of the most difficult the continent,[by whom?]

The Chaco area is famous for the large number of hunters who visit, despite a ban on hunting of endangered animals.