Wrong. It's the Gran Chaco.
When the Spaniards trudged across the great plains of the Chaco in South America they found no gold or silver or fabled cities and moved on. In the years since their arrival little has changed in the enormous area where few inhabitants struggle with the environment to make a living.
This map which I sectioned from a National Geographic map, is certainly not accurate as far as the borders of the Chaco but it will give you an idea. The Chaco stretches through the southeastern corner of Bolivia portions of Argentina Paraguay and Brazil. It is a vast (c.250,000 sq mi or 647,500 sq km) parched lowland plain supporting grasslands thorny forests and cactus. The weather is hot, one of the hottest places in South America and flood seasons alternate with drought. The hard clay soil makes agriculture difficult.
In Bolivia the Chaco is all but ignored. An almost inpenetrable area of thorn and cactus makes this area is inhospitable to Bolvians and uninviting to tourism. In Brazil the Chaco is known as the Mato Grosso and until the late 1970's was one large state. Now divided into Mato Grosso and Mato Grosso do Sul this area of Brazil also blends into the Pantanal the huge wetlands area. In the Mato Grosso there is a concerted effort at development with road construction and agricultural development eating away at the native environment.
In the early thirties the Chaco was believed to be a source of oil. Two large oil companies Standard and Shell were involved in the exploration. Competition between the Bolivia and Paraguay over oil rights and the oil companies for these potential oil deposits was heated and eventually led to the Chaco War of 1932 - 1935. Standard Oil backed Bolivia which at that time owned more of the Chaco than it does now. Shell was on Paraguay's side. Even though Bolivia had a large army the highland native soldiers did poorly on the Chaco where the fighting conditions favored the Paraguayan forces. Bolivia suffered heavy losses, in troops pride and land when it lost the war and had to cede 225,00 sq km to Paraguay.
Oil was not found then and after hostilities ceased the native flora and fauna continued undisturbed.
Paraguay now had more territory and the Chaco occupies much of the portion of the land from the western banks of the Rio Paraguay which bisects the country from north to south. Gerhard Roux in Paraguay describes it as the largest region in the country and is also the least populated. It covers a area of 95,337 square miles (244,00 km2) about 61 percent of the whole Paraguayan territory. However it is inhabited by only a little more than 2 percent of the nations's population. Nonetheless the peculiar landscape of El Chaco and its exclusive fauna and flora make it uniquely interesting to tourists.
The Chaco can be reached by boat or highway on the Trans-Chaco route. Nature lovers can enjoy excursions and ride or horseback through almost unexplored areas both in Alto Chaco where rainfall is minimal and in Bajo Chaco an area of big swamps and forests of quebracho and palo santo (holy wood).
There are more than 500 kinds of hardwood trees in this region and approximately 300 types of medicinal plants including such unusual varieties as cactus and "sumu'u" a big-bellied tree. Many different birds can be seen in this region such as the South American ostrich and also wild beasts like jaguars, ocelots brown wolves waterhogs (carpincho) pumas and others.
The drive from Asunción leads through the Low Chaco a land of palm forests and marshes and reaches the Middle Chaco with its capital Filadelfia. Here Mennonites of German descent have set up farms and other agricultural outlets as well as their own schools and are considered to be the only organised community in the whole of the Chaco region.
Even though areas of the Chaco are largely unexplored Paraguay has managed to "tame" some of it for cattle raising agriculture and the lumber industry. The terrain includes palm reeds scrub forest grassy savanna and dense growths of spiny brush. The savanna is used for cattle ranching and cotton growing and the forested part in Paraguay and northern Argentina is noted for its timber.