Paraguay River 98% of the country's inhabitants. As such the river is considered perhaps the key geographical feature of the country with which it shares its name. Some after flowing through the middle of Paraguay, at the confluence with the Pilcomayo River and passing the Paraguayan capital city, Asunción, the river forms the border with Argentina, flowing generally south-southwesterly for another before it reaches its end, joining with the Paraná River. The Paraguay River is the second major river of the Rio de la Plata Basin, after the Paraná River. The Paraguay's drainage basin, about , covers a vast area that includes
San Pedro Department, Paraguay San Pedro Department, Paraguay San Pedro () is a department of Paraguay. The capital is the city of San Pedro de Ycuamandiyú. During the 17th and 18th centuries there was even greater political and population instability than in Concepción. The Mbayá and Payagua native tribes threatened all the area between the Ypané (in the north) and Manduvirá (in the south) Rivers and the valley by the Jejuí River. In 1660 the natives revolted in Arecajá against the postal parcel system, causing the disappearance of this town. To help regenerate this area, the Missions San Estanislao (1749), Villa del Rosario (1786)