The country between the Huallaga and the Ucayali, traversed by the Eastern Cordillera, is called the Pampa del Sacramento, and is characterized by extensive grassy plains.
Both pampa and iptvis, according to Farnell, are epithets of Demeter as an earth-goddess of the under-world.
Between the Supe and Pativilca is the desert called the Pampa del Medio Mundo.
The Charruas are generally classified as a yellow-skinned race, of the same family as the Pampa Indians; but they are also represented as tanned almost black by the sun and air, without any admixture of red or yellow in their complexions.
San Luis belongs partly to the semi-arid pampa region, and partly to the mountainous region of the eastern Andes and Cordoba whose ranges terminate between the 33rd and 34th parallels.
The recent deposits, which cover so large a part of the depression between the Eastern and the Western Cordillera, appear to be partly of torrential origin, like the talus-fans at the foot of mountain ranges in other dry regions; but Lakes Titicaca and Pampa Aullaguas (Poopo) were undoubtedly at one time rather more extensive than they are to-day.
The La Pampa territory also is dotted with small lakes.
In 1881 President Roca offered for public purchase by auction the lands in the southwest of the province of Buenos Aires, the Pampa Central, and the Neuquen district, these lands having been rendered habitable after the campaign of 1878 against the Indians.
It possesses only one large river in Bolivia, the Pilcomayo, which rises on the east slopes of the Cordillera Oriental opposite the south end of Lake Pampa Aullaguas and flows east and south-east through the sierra region to the Bolivian Chaco.
The principal Bolivian tributary of the Mamore, the Guapay or Grande, which is larger and longer than the former above their confluence and should be considered the main stream, rises in the Cordillera Oriental east of Lake Pampa Aullaguas, and flows east to the north extremity of the Sierra de Misiones, where it emerges upon the Bolivian lowlands.