The Gran Chaco is South America's second-largest forested ecoregion, smaller only than the Amazon. Its character varies dramatically across its breadth. In the west, the Alto Chaco -- the Dry Chaco -- is sparse and punishing, where white quebracho and red quebracho trees rise from sandy soil alongside towering columnar cacti like Stetsonia coryne. Move east and the landscape softens into the Bajo Chaco, where higher rainfall feeds swampy plains carpeted with Copernicia alba palms and tropical bunch grasses. The transition between these zones is not abrupt but gradual, a slow shift in moisture and density that reveals itself over hundreds of kilometers. More than 3,400 plant species inhabit the region. The quebracho -- whose name derives from quiebra-hacha, or "axe-breaker," for the density of its wood -- sustained a tannin extraction industry for decades, with dedicated factories built to process its bark. Palo santo wood from the central Chaco produces oil of guaiac, a fragrance used in soaps.

The Argentinian Chaco holds the world's greatest concentration of armadillo diversity, home to at least ten species. The nine-banded armadillo, whose range extends as far north as the southern United States, is the cosmopolitan member of the group. The southern three-banded armadillo curls into a near-perfect ball when threatened. And then there is the pink fairy armadillo -- palm-sized, pale rose, burrowing through sandy soil with oversized front claws -- a creature so improbable it seems designed by committee. The giant armadillo, weighing up to 50 kilograms, roams the drier western reaches. Above the understory, 409 bird species breed or reside in the Chaco, 252 of them endemic to South America. The black-legged seriema stalks through the scrub on long legs. Blue-crowned parakeets flash through the canopy. The many-colored Chaco finch, its plumage a patchwork of subtle hues, sings from thorn branches that would tear any hand reaching for it.

The Chaco's political history is a paradox: nations fought bitterly over land that none of them could effectively govern. After Paraguay's defeat in the War of the Triple Alliance in 1870, Argentina fixed its border at the Bermejo River. Bolivia, landlocked since losing its Pacific coast in the War of the Pacific, eyed the Paraguay River as a shipping route for oil and began settling the Chaco from the west. Paraguay claimed the land but largely ignored it. The collision came in the Chaco War of 1932-1935, one of South America's bloodiest conflicts, fought over territory rumored to contain oil reserves. Argentine Foreign Minister Carlos Saavedra Lamas mediated the 1938 treaty that gave Paraguay three-quarters of the Chaco Boreal and Bolivia a corridor to the Paraguay River. The irony cut deep: no oil was found in the disputed territory until 2012. Meanwhile, a wholly different kind of settler had arrived. Canadian Mennonites established colonies in the Paraguayan Chaco during the 1920s, followed by refugees from the Soviet Union in the 1930s. Their descendants built some of the most prosperous communities in the deep Chaco.

The Gran Chaco is now one of the world's most active deforestation frontiers. Between 2000 and 2019, the Dry Chaco lost an estimated 20.2 percent of its forest cover. Argentina alone saw seven million hectares disappear between 1998 and 2023 -- roughly 1,130 hectares cleared per day according to the local NGO Fundacion Avina. Cattle ranching and soybean farming drive the destruction, backed by international agribusiness giants. Indigenous communities -- the Wichi, Qom, Pilaga, Guarani, Ayoreo, and others who have inhabited the Chaco for centuries -- are losing their lands to the expanding agricultural frontier. Conservation efforts exist: Bolivia's Kaa-Iya National Park protects a significant portion, and 22 percent of the ecoregion falls within designated protected areas. But enforcement is weak, illegal logging persists, and the Chaco's sheer remoteness -- the Trans-Chaco Highway was not built until the 1960s -- makes oversight difficult. Paraguay, which lost more than 90 percent of its Atlantic rainforest between 1975 and 2005, is now watching its xerophytic Chaco forests follow the same trajectory.