The Chaco Boreal (Gran Chaco) is a 647,000 sq Km area west of the Paraguay river and East of the Andean foothills in Paraguay, Bolivia and Argentina.
"In the west, near the mountains, the Gran Chaco is a flat, sparsely vegetated, waterless plain. Further east it is a thick, dry, almost impassable thornbrush jungle punctuated by dense stands of quebracho trees and grassy clearings.
There are few people, but myriad biting, stinging insects and many tropical diseases. Prior to 1928, the region's only real value was the tannin extracted from its quebrachos and the meager grazing it provided for cattle.
The Gran Chaco conflict was, in fact, largely a war of engineers. Cutting trails through the jungle, building roads, erecting field fortifications, and, above all, locating and drilling wells were the activities that determined the pace and outcome of battles. The Chaco was largely without potable surface water, even where vegetation was thickest. Before attacks could be mounted or ground held, water for men and horses had to be brought forward by truck. Trucks and gasoline were always in such short supply that their availability decided the timing of offensives or the feasibility of holding ground. Neither belligerent could afford to purchase the vehicles in the requisite numbers, and wastage was high in the rough, roadless Chaco. To make the best use of the trucks, the distance between water sources and the front had to be kept short." (
http://www.worldatwar.net/chandelle/v1/v1n3/chaco.html)
Temperatures topped 100 degrees every day!
"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."
http://gosouthamerica.about.com/cs/southamerica/a/ParGranChaco.htm
But I was mistaken about the Altitude. My apologies! It is less than 3,500 meters. but it is between 1,000 and 2,500 meters and slopes down toward Paraguay. Once again, lower than I thought at first. sorry. Still a desert though!
P.S. Patagonia is a desert in a similar sense that people once thought the Great Plains of the U.S. were the "Great American Desert". Just because a dry wind blows through the Sandhills of Nebraska (which are beautiful like Patagonia) doesn't make it a "desert". It's just a drier area. But I won't dispute Patagonia as a desert for HoI purposes, on the game's perspective it is a desert. But I wouldn't call it a desert to my friend Tomas from there. Or to any of those crazy Welsh bastards that herd sheep down there