Long before the arrival of the Europeans, the Paraguay River was already a route of life and transit. Its shores and the lands it waters were inhabited by Guaraní peoples and other Chaco ethnic groups, who used the river for fishing, canoe transport and the cultivation of the fertile riverside lands. The river structured the territory: it separated the forests of the Eastern region from the vast western Chaco, and connected communities across hundreds of kilometers.
Guaraní culture left its indelible mark on the toponymy and on the very language still spoken in the country. The name 'Paraguay' is usually associated with Guaraní, with interpretations tied to water and the river, though its exact meaning is the subject of debate. What is certain is that the river was, for these peoples, much more than a geographical feature: it was an axis of subsistence, mobility and worldview.
When the first European expeditionaries went up the river in the sixteenth century seeking a route to the riches of the interior and Peru, they found a river world already densely lived in. That indigenous population and their knowledge of the river would be decisive in what came next: the founding of a Spanish city on its shores and the birth of a mestizaje that defines Paraguay to this day.
The Paraguay River was the gateway of the Spanish conquest into the heart of South America. In the early sixteenth century, expeditions like those of Juan de Ayolas and Domingo Martínez de Irala went up the river in search of a passage to the riches of the highlands. In August 1537 Nuestra Señora Santa María de la Asunción was founded on its shores, at a point that offered a good port and relations with the local Guaraní.
Asunción became the base of the Spanish expansion throughout the Plata basin: from it set out the expeditions that founded or re-founded cities like Buenos Aires, Santa Fe, Corrientes and others, earning it the nickname 'Mother of Cities'. The Paraguay River was the umbilical cord that linked the nascent province with the outside world, in a territory with no direct sea outlet and completely dependent on river navigation.
During the colonial period, the river was a route of trade —yerba mate, tobacco, hides— and of communication with Buenos Aires and the Atlantic. That dependence on the river shaped the destiny of Paraguay as a landlocked country, whose prosperity and isolation depended on control of the waterways. The history of the river is, to a large extent, the very history of the country's formation.
For its strategic value, the Paraguay River was the scene of decisive episodes of national history. During the War of the Triple Alliance (1864-1870), which pitted Paraguay against Brazil, Argentina and Uruguay, control of the river was key: the allied fleets went up its waters and river and land battles were fought along its course. The defeat left the country devastated, but the river remained, in the subsequent reconstruction, the main outlet for its production.
In the twentieth century, the Chaco War (1932-1935) against Bolivia again put the river at the center: it was the supply route toward the Chaco front, and its control proved essential for Paraguayan logistics. The river connected the rear with an inhospitable and thirsty theater of operations, where water was a scarce and disputed commodity.
In 1969, Argentina, Bolivia, Brazil, Paraguay and Uruguay signed the Treaty of the Plata Basin, the seed of what would be the modern Paraguay-Paraná Waterway. In 1987, gathered in Santa Cruz de la Sierra, the foreign ministers of the five countries declared the development of that river system a priority interest, laying the legal foundations of the navigation corridor we know today.
In its northern stretch, before entering the most populated territory of the country, the Paraguay River rises and crosses the Pantanal, the largest continuous tropical wetland on the planet, shared between Brazil, Bolivia and Paraguay. The Pantanal works as an immense natural sponge that regulates the flow of water, buffers the floods and stores enormous amounts of carbon, and the Paraguay River is its main collector: through it flows much of the water that enters and leaves that ecosystem.
The biodiversity of this region is extraordinary. According to estimates by the World Wide Fund for Nature (WWF), the Pantanal houses around 656 bird species, 159 mammal species, 325 fish species, 98 reptile species and 53 amphibian species, plus thousands of plant species. On the shores of the Paraguay River and in its marshes coexist the caiman (which plays a key role as a regulator of the fish fauna), the capybara, the marsh deer and emblematic birds like the jabiru —the largest stork in the Americas— and the hyacinth macaw.
This natural richness made the northern stretch of the river, around Bahía Negra and Fuerte Olimpo, one of the great destinations of nature and river tourism in Paraguay, and led to the Paraguayan Pantanal being included on UNESCO's tentative World Heritage list, in recognition of its unique ecological value.
Today, the Paraguay-Paraná Waterway is a navigation corridor of more than 3,400 kilometers that connects ports of Bolivia, Brazil, Paraguay, Argentina and Uruguay, and constitutes one of the most important commercial arteries of South America. Since the late 1990s, Paraguay developed the largest barge fleet in the region, and today moves by this waterway several million tons of cargo a year —mainly grains, like soybeans—, this being the way a landlocked country exports much of its production toward the Río de la Plata and the Atlantic Ocean.
Alongside this commercial role, in recent decades interest in river tourism on the Paraguay River has resurfaced. Specialized operators offer cruises of several days that go up the river from Asunción or Concepción toward the north, with stops in Vallemí, Fuerte Olimpo and the Pantanal area, re-creating in a tourist key the old navigation route that for centuries linked the country's riverside populations.
The Paraguay River thus remains what it was since pre-Hispanic times: the backbone of the country, now divided among the trade of the waterway, sport fishing, wildlife watching and the nature tourism that draws travelers from around the world toward the river heart of South America.