Exploration. – In the long period of Spanish domination (for the discovery and conquest, see below) the missionaries and the Jesuits contributed to widening the knowledge of the country, but foreign travelers were systematically kept away, allowing only French scholars to penetrate the interior starting from 1700. We remember among them Frezier who in the first years of the century traveled the plateau of Peru and Bolivia.

According to Ehotelat, in the last twenty years of the same century the activity of the geodetic mission presided over by La Condamine and that of Felice de Azara took place who between 1781 and 1802 studied and described all the provinces of Spanish America. Finally, the explorations of Alexander v. Humboldt, who studied in particular the volcanoes of Ecuador and Peru, closed this first period of scientific research.

In the century XIX, during the struggles for independence and the continuous political turmoil that followed the formation of the new state, the exploration work was carried out almost exclusively by European and North American travelers, but they mainly applied themselves to the study of the relics of the ancient Inca civilization and that of the ‘ethnology. However, the travels of J.-B. Boussingault (1825-31) who visited northern Peru, by JB Pentland (1826-28) who studied geology and botany, by A. D’Orbigny who in 1833 traveled the Peruvian coast coming from Bolivia, by E. Pöppig (1830-1831) which crossed the Cordillera between Lima and Cerro de Pasco and descended the Huallaga, by F. de Castelnau, and finally by JJ von Tschudi who remained in Peru from 1838 to 1842 and returned there in 1858, however, devoting himself particularly to archaeological research. In 1850 the Italian A. Raimondi arrived in Peru, who holds the first place in the history of the country’s geography. For forty years (1850-90) he dedicated all of himself to the study of Peru, subsequently traveling through all the provinces and consecrating the results of his long effort in two works that still remain fundamental even if unfortunately unfinished: El Perú, in 3 volumes, and the large map of Peru at the scale of 1: 500. o00 in 34 sheets. After 1875 we can still remember the travels of W. Reiss and A. Stübel who reached Huallaga from Pacasmayo, and of A. Wertheman (1876-79) who studied hydrography and drew some maps of northern Peru. This was followed by the explorations of O. Ordireire (1885), YP James (1886) and R. Payer (1891) aimed at finding an easy way between Lima and the eastern lowlands through the Cordillera. Also important is the work of EM Middendorf who lived for many years in Peru and carried out archaeological and ethnographic research there, whose work, however, is also of considerable interest to the geographer.

At the same time the activity of Peruvian scholars took place, particularly notable after the establishment of the Geographic Society founded in Lima in 1888. In addition to MF Paz Soldán, who carried out geographical research in northern Peru and published a geography of Peru, we remember F. Moreno, who studied oil fields (1891-93), R. Paz, who traveled the region between Riberalta and Inambari (1895), IT Caucino, who studied the province of Ayacucho (1893), CA Pérez (1893) and FG Sala (1903), who explored the rivers Pichis, Palcazú, Pachitea and the upper Ucayali, CR Cisneros and RE Gart. ía, who published a study on the Libertad department (1900), CJ Lisson, who studied fossils and their distribution (1913), the Rosa Toro, who dealt with ethnography, and others, while continuing the the work of foreign travelers such as A. Hettner, R. Payer, W. Sievers, J. Bowman, JA Douglas, TO Bosworth, H. Gerth, HG Gregory, Ch. W. Douville-Fife, and others who in the first quarter of the century. XX especially studied geology and ethnography.

Borders. – The borders of Peru have not yet been completely fixed, as a vast territory between the Marañón and the Napo-Putumayo watershed is in dispute with Ecuador. Ecuador, as heir to Colombia in the border with Peru (the dispute dates back to the time of the separation of Ecuador from Colombia), demands that the borders be brought to the Marañon, as was established in the Treaty of Guayaquil of 22 September 1829 (with the modifications made by the Pedemonte-Mosquera protocol of 1830); Peru, on the other hand, makes claims over a large part of the Ecuadorian East, and effectively exercises its authority over the lower basins of Napo, Tigre and Pastaza. With Colombia, disputes arose in 1932 for the possession of the trapezoidal territory of Loreto and Leticia, between the Putumayo and the Amazon River, which Peru had recognized as Colombian in the 1922 treaty with Colombia, ratified by it in 1925 and by Peru itself in 1927. After a brief conflict, the question was submitted to the League of Nations, who decided in favor of the Colombian thesis. The Colombian-Peruvian border, about 1350 km long, is therefore marked by the Putumayo river up to the 70th meridian west, and then by a line that goes NE.-SO. it goes from the Putumayo to the Amazon River; finally, from a stretch of the Amazon to Tabatinga. Here begins the border with Brazil, 1900 km long. and marked for a long stretch by the river Yavarí (Javary) and then by the Sierra de la Frontera. It was defined, in general terms, from 1851; the section between the sources of the Yavarí and the Río Acre was definitively fixed in 1909. The border with Bolivia, which is partly marked by the Río Heath, tributary of the Madre de Dios, and crosses Lake Titicaca, of which the the western part is 890 km long; its delimitation gave rise to serious controversies, especially for the stretch immediately north of Titicaca (Apolobamba region), which was then established between 1911 and 1913 by an English commission. But the most serious dispute with neighboring states for border issues was that with Chile, which from the time of the war of 1879-1883 had occupied the Peruvian province of Tacna and Arica, in which a plebiscite should have been carried out after ten years to decide on their definitive membership. The plebiscite never took place and the two states remained without diplomatic relations for many years, and indeed were on the point of resorting to arms again several times. The question was resolved, through the intervention of the United States, only in 1929: on June 3 of that year a treaty was signed between Peru and Chile, with which the border between the two states (about 120 km long) was set at 10 km. north of the Arica-La Paz railway. So Tacna returned to Peru, and Arica remained in Chile.) was set at 10 km. north of the Arica-La Paz railway. So Tacna returned to Peru, and Arica remained in Chile.) was set at 10 km. north of the Arica-La Paz railway. So Tacna returned to Peru, and Arica remained in Chile.

The Peruvian coasts have a development calculated on 2700 km.

Surface. – The uncertainty of the borders with Ecuador means that the area of ​​Peru is very differently estimated. The official figure is 1,365,054 sq km, but recent cartometric measurements assign to Peru, even including the territory in dispute with Ecuador, 1,249,000 sq km. only (according to other sources, 1,300,000 sq. km.). However, Peru area is the 3rd state of South America, coming after Brazil and Argentina, and occupying about ¹ / ₁₄ of the total area of that part of the world. Its surface corresponds to more than 4 times that of Italy. The population according to an estimate as of January 1933 amounts to 6,600,000 residents (4th place among the South American states), 5 per sq. Km.

Peru is between 0 ° 10 ′ N. (Ecuadorian Peruvian-Colombian border at the confluence of Sucumbios with Putumayo) and 18 ° 20 ′ S. (border with Chile north of Arica), and between 68 ° 40 ′ (border with Bolivia east of Puerto Maldonado) and 81 ° 54 ′ (Punta Pariña) O.