[1] Archaeologists have identified and excavated a number of these ritual centers; the first of these to be discovered was that at Kotosh, although since then further examples have been found at Shillacoto, Wairajirca, Huaricoto, La Galgada, Piruru,[2] among others.

[7] The first archaeologist to investigate the site at Kotosh was Julio C. Tello, the "father of Peruvian archaeology", who visited it in 1935 as a part of his wider general survey of the Huallaga basin.

[7] In 1958, the Japanese archaeologist Seiichi Izumi visited the site, accompanied by Julio Espejo Núñez of the Museo Nacional de Arqueología, Antropología e Historia del Perú and Professor Luis G. Lumberas of the San Cristóbal of Huamanga University.

[7] Following on from this visit, Izumi led a team from the University of Tokyo, Japan on an excavation of the site from 1 July to 3 October 1960,[7] as a part of their wider Andean Research Program, which had been going on since 1958.

[11] The archaeologists who excavated at the site in the late 1970s and early 1980s decided to call the monument "La Galgada" after the nearest town, a coal-mining settlement about 2 kilometres to the north, although local people instead referred to it as "San Pedro".

[10] It is clear from the archaeological evidence that they spent more effort in constructing the various ceremonial and mortuary monuments than in homes for themselves, an approach common to most pre-modern societies across the world.

[12] Archaeological surveys have established that during the Pre-Ceramic Period, at least 11 settlements had grown up throughout the Tablachaca Canyon, being concentrated on both sides of the river for at least 8 km near to the modern village of la Galgada.

[13] This led one of the head excavators, Terence Grieder, to comment that the La Galgada site must be seen as "one of the most important ceremonial and burial areas in a larger, well-populated district, which in Pre-ceramic terms must be considered virtually a metropolitan center".