Paraguay River in the context of "Paraná River"

The Río de la Plata basin (Spanish: Cuenca del Plata, Portuguese: Bacia do Prata), more often called the River Plate basin in scholarly writings, sometimes called the Platine basin or Platine region, is the 3,170,000-square-kilometre (1,220,000 sq mi) hydrographical area in South America that drains to the Río de la Plata. It includes areas of southeastern Bolivia, southern and central Brazil, the entire country of Paraguay, most of Uruguay, and northern Argentina. Making up about one fourth of the continent's surface, it is the second largest drainage basin in South America (after the Amazon basin) and one of the largest in the world.

The main rivers of the La Plata basin are the Paraná River, the Paraguay River (the Paraná's main tributary), and the Uruguay River.

The Guarani are a group of culturally-related Indigenous peoples of South America. They are distinguished from the related Tupi by their use of the Guarani language. The traditional range of the Guarani people is in what is now Paraguay between the Paraná River and lower Paraguay River, the Misiones Province of Argentina, southern Brazil once as far east as Rio de Janeiro, and parts of Uruguay and Bolivia.

Although their demographic dominance of the region has been reduced by European colonisation and the commensurate rise of mestizos, there are contemporary Guarani populations in Paraguay and parts of Argentina and Bolivia. Most notably, the Guarani language, still widely spoken across traditional Guarani homelands, is one of the two official languages in Paraguay, the other one being Spanish. The Paraguayan population learns Guarani both informally from social interaction and formally in public schools. In modern Spanish, Guaraní also refers to any Paraguayan national in the same way that the French are sometimes called Gauls.

Asunción (English: /ɑːˌsuːnsiˈoʊn, ˌɑːsuːnˈsjoʊn/, Spanish: [asunˈsjon]; Guarani: "Paraguay") is the capital and the largest city of Paraguay. The city stands on the eastern bank of the Paraguay River, almost at the confluence of this river with the Pilcomayo River. The Paraguay River and the Bay of Asunción in the northwest separate the city from the Occidental Region of Paraguay and from Argentina in the south part of the city. The rest of the city is surrounded by the Central Department.

Asunción is one of the oldest cities in South America and the longest continually inhabited area in the Río de la Plata Basin; for this reason it is known as "the Mother of Cities". From Asunción, Spanish colonial expeditions departed to found other cities, including the second foundation of Buenos Aires, that of other important cities such as Villarrica, Corrientes, Santa Fe, Córdoba, Santa Cruz de la Sierra and 65 more. According to the 2022 Paraguayan Census, Asunción has 462,241 inhabitants, while its metropolitan area (known as Greater Asunción) exceeds 2.3 million inhabitants, making it the most densely populated area in Paraguay, and also the most productive as it concentrates 70% of the National GDP. Asunción is the third most populated "jurisdiction" or "political division" in the country, surpassed by the Central and Alto Paraná departments.

The Pampas (/ˈpæmpəz/; from Quechua pampa 'plain'), also known as the Pampas Plain, are fertile South American low grasslands that cover more than 1,200,000 square kilometres (460,000 sq mi) and include the Argentine provinces of Buenos Aires, La Pampa, Santa Fe, Entre Ríos, and Córdoba; all of Uruguay; and Brazil's southernmost state, Rio Grande do Sul. The vast plains are a natural region, interrupted only by the low Ventana and Tandil hills, near Bahía Blanca and Tandil (Argentina), with a height of 1,300 m (4,265 ft) and 500 m (1,640 ft), respectively. This ecoregion has been changed by humans, especially since the release of animals like cattle, pigs, and especially sheep onto these plains.

The climate is temperate, with precipitation of 600 to 1,200 mm (23.6 to 47.2 in) that is more or less evenly distributed throughout the year, making the soils appropriate for agriculture. The area is also one of the distinct physiography provinces of the larger Paraná–Paraguay plain division.

The red-bellied piranha, also known as the red piranha (Pygocentrus nattereri), is a species of freshwater ray-finned fish belonging to the family Serrasalmidae, which includes the pacus, piranhas and related fishes. The red-bellied piranha occurs in South America, found in the Amazon, Paraguay, Paraná and Essequibo basins, as well as coastal rivers of northeastern Brazil. This fish is locally abundant in its freshwater habitat.

They are carnivorous foragers and feed on insects, worms, crustaceans and fish. Opportunistic feeders as they are, will also take advantage of edible aquatic plants as well as any fruits, nuts or seeds that may fall into the waters. They are not a migratory species but do travel to seek out conditions conducive to breeding and spawning during periods of increased rainfall. Red-bellied piranhas often travel in shoals as a predatory defense but rarely exhibit group hunting behavior. Acoustic communication is common and is sometimes exhibited along with aggressive behaviors. They are a popular aquarium fish.