Having done the other large Southern Cone state earlier, here is the other one. Chile is noted perhaps first of all for its strange shape. Now the Andes does somewhat explain part of its border with Argentina as a 'natural' barrier but that hardly explains the whole length of it nor its precise breadth never mind the straight line that goes through Tierra Del Fuego or the northern borders with Peru or Bolivia. In the world which became colonial (so nearly all of it outside of Europe and East Asia) borders were frequently creations of administrative convenience with little reference to local conditions. In Europe on the other hand borders were primarily negotiated territory which shifted back and forth between various owners (can't really speak of countries especially before Westphalia), centuries of conquest, counter-conquest, deals and counter-deals shaped Europe's less perpendicular more 'natural' borders of today. In Europe in other words power created the state which created bureaucracy which ruled over the land (and the people who lived on it) which eventually after centuries formed a people (needless to say this is a simplification, and was very different wherever you went in Europe). What land exactly was usually in flux. In the Americas on the other hand power created the bureaucracy which ruled over the land and its people which eventually led to the state and the creation of a people. Latin America is particularly interesting case for this because what, exactly, differed Chileans from Argentinians, Paraguayans from Uruguayans, Colombians from Mexicans? At least among the Creole populations which ran these countries post-independence. The people who live in these countries now no doubt feel 'Chilean' or 'Colombian' but what did that mean in 1800? Chile is especially interesting in this because its growth as a territory shows signs of both the European and the American styles I referred to earlier.
Originally it was the Captaincy General of Chile. Its formation was a process that lasted the sixteenth century from 1530 onwards, beginning, of course, with a Spanish expedition that hoped to outdo Pizarro and Cortes and find another kingdom of gold. When gold was not forthcoming, settlement was preferred, and along the Andean ridge south of Peru came to be founded and recognized by central authority a new unit in Spanish America, called Chile. Its borders were defined to its North by Peru, the wealthier more important political unit to its north, of which Chile - a mere captaincy general to Peru's Viceroyalty - was a part, to its east by what was then mostly uninhabited (by Europeans) territory blocked off by the Andes and by its south by the various Patagonian indigenous people who were described generally as Araucanians. These were fierce warlike people who regularly put a stop to any intended European expansion. Until well into the 19th century and after independence Chile claimed all of Patagonia of its territory. But generally it was a backwater in the empire. In the 19th Century technology and a more efficient state allowed the eventual march southwards of Chileans (a mixture of Basques, Italians, Spaniards, and Germans) and cleansing of a lot of its 'Araucanian' population even if it was never quite as genocidal as it was in Argentina. Agreements with the Argentinians though, and the more powerful nature of that state, meant that Patagonia was partitioned awkwardly but with a line from Santiago going directly south along its present border, rarely deviating west. To the north expansion was achieved during an absurdly unjust war (1879-1883), primarily fought over guano deposits, with Peru and Bolivia in which the country annexed Bolivia's only coastal region and part further North which belonged to Peru. Today there is little desire for inhabitants of these regions to rejoin their original nations, such is the nature of nationalism. Chile has thousands of kilometers of coastline and this annexation still brings up strong feelings among Bolivians today, where hate Chile is a common political sentiment. This annexation did not move the country much further to the East, it stuck to hugging the coast.
With the War of the Pacific and the Occupation of Araucanía Chile included in its borders the driest place on Earth (Atacama Desert) to glaciers and the lowest temperatures in South America in its Central and Southern interior to a more Mediterranean climate on its central coast and to cool and oceanic in its southern coast often with high rainfall. It crosses 38 degrees of Latitude so speaking of seasons nationally is incoherent; more than 4,200km north to south but only at its widest, 177km east to west. No European state could ever achieve this sort of climatic diversity. In terms of fauna and flora it is also especially diverse with the Atacama and Andes acting as barriers creating many endemic species. Perhaps the one geographical feature that does unite the country is earthquakes. Nearly all of Chile is on the border between the Nazca Plate and the South American Plate, and the borders between those two and the Antarctic Plate. Thus it is extremely earthquake prone with some of the strongest earthquakes recorded happening on its coast, including the strongest ever
recorded in 1960. Resultant Tsunamis are also a big danger. This though hardly the basis for a creation of a homogeneous state or a people, which Chile, despite its minority including its still remaining Mapuche, as the main Araucanian group became known as (about 600,000 of them in the last census, and that included only those who could either still speak their language or practiced native customs), is today. A Europeanized mass despite the constant tensions which flame up into regular conflicts between them and the remaining indigenous.
Below are a series of maps concerning the indigenous populations of Chile (and Argentina). The first image is on its left a general map of the Southern Cone with three indigenous cultural identified - Andeans in the North, Mapuche in the Middle, and Fuegans in the South. On the right then is a series of map sorted by date showing the spread of the Mapuche people across Chile, although today even in the Araucanía region they only make up about a third of the population (so about 300,000 in the region). Of those maps the one on the left translates as "Mapuche territory according to ancestral knowledge" fwiw. The second image is of a map of Patagonia showing the ancestral indigenous ethnicities by area. Many of these groups are extinct or near extinct now.