Europe

One of the cairns at Carrowkeel Megalithic Cemetery in Ireland, which covers a passage tomb.

The building of cairns for various purposes goes back into prehistory in Eurasia, ranging in size from small rock sculptures to substantial human-made hills of stone (some built on top of larger, natural hills).^[2] The latter are often relatively massive Bronze Age or earlier structures which, like kistvaens and dolmens, frequently contain burials; they are comparable to tumuli (kurgans), but of stone construction instead of earthworks.^[3] Cairn originally could more broadly refer to various types of hills and natural stone piles, but today is used exclusively of artificial ones.

Cairn of the Neolithic-era passage tomb on Gavrinis island, Brittany

North and northeast Africa

Ancient cairns in Qa'ableh, Somaliland

Cairns (taalo) are a common feature at El Ayo, Haylan, Qa'ableh, Qombo'ul, Heis, Salweyn and Gelweita, among other places. Somaliland in general is home to a lot of such historical settlements and archaeological sites wherein are found numerous ancient ruins and buildings, many of obscure origins.^[10] However, many of these old structures have yet to be properly explored, a process which would help shed further light on local history and facilitate their preservation for posterity.^[11]

Since Neolithic times, the climate of North Africa has become drier. A reminder of the desertification of the area is provided by megalithic remains, which occur in a great variety of forms and in vast numbers in presently arid and uninhabitable wastelands: cairns (kerkour), dolmens and circles like Stonehenge, underground cells excavated in rock, barrows topped with huge slabs, and step pyramid-like mounds.^[12]

Middle East

Cairn in the Judean mountains

The Biblical place name^[13] Gilead (Genesis 31 etc.) means literally "heap of testimony/evidence" as does its Aramaic translation (ibid.) Yegar Sahaduta. In modern Hebrew, gal-'ed (גל-עד) is the actual word for "cairn". In Genesis 31 the cairn of Gilead was set up as a border demarcation between Jacob and his father-in-law Laban at their last meeting.^[14]

Asia and the Pacific

A Mongolian ceremonial cairn (ovoo)

Starting in the Bronze Age, burial cists were sometimes interred into cairns, which would be situated in conspicuous positions, often on the skyline above the village of the deceased. Though most often found in the British Isles, evidence of Bronze Age cists have been found in Mongolia.^[15] The stones may have been thought to deter grave robbers and scavengers. Another explanation is that they were to stop the dead from rising. There remains a Jewish tradition of placing small stones on a person's grave as a token of respect, known as visitation stones, though this is generally to relate the longevity of stone to the eternal nature of the soul and is not usually done in a cairn fashion.^[16] Stupas in India and Tibet probably started out in a similar fashion, although they now generally contain the ashes of a Buddhist saint or lama.

A traditional and often decorated, heap-formed cairn called an ovoo is made in Mongolia. It primarily serves religious purposes, and finds use in both Tengriist and Buddhist ceremonies. Ovoos were also often used as landmarks and meeting points in traditional nomadic Mongolian culture. Traditional ceremonies still take place at ovoos today, and in a survey conducted, 75 participants out of 144 participants stated that they believe in ovoo ceremonies. However, mining and other industrial operations today threaten the ovoos^[17]

In Hawaii, cairns, called by the Hawaiian word ahu, are still being built today. Though in other cultures, the cairns were typically used as trail markers and sometimes funerary sites, the ancient Hawaiians also used them as altars or security tower.^[18] The Hawaiian people are still building these cairns today, using them as the focal points for ceremonies honoring their ancestors and spirituality.^[19]

In South Korea, cairns are quite prevalent, often found along roadsides and trails, up on mountain peaks, and adjacent to Buddhist temples. Hikers frequently add stones to existing cairns trying to get just one more on top of the pile, to bring good luck. This tradition has its roots in the worship of San-shin, or Mountain Spirit, so often still revered in Korean culture.^[20]

The Americas

Throughout what today are the continental United States and Canada, some Indigenous peoples of the Americas have built structures similar to cairns. In some cases, these are general trail markers, and in other cases they mark game-driving "lanes", such as those leading to buffalo jumps.^[21]

Peoples from some of the Indigenous cultures of arctic North America (i.e. northern Canada, Alaska and Greenland) have built carefully constructed stone sculptures called inuksuit and inunnguat, which serve as landmarks and directional markers. The oldest of these structures are very old and pre-date contact with Europeans. They are iconic of the region (an inuksuk even features on the flag of the Canadian far-northeastern territory, Nunavut).^[22]

Cairns have been used throughout what is now Latin America, since pre-Columbian times, to mark trails. Even today, in the Andes of South America, the Quechuan peoples build cairns as part of their spiritual and religious traditions.^[23]

Sea cairns

Sea mark in Finnish coastal waters

Coastal cairns called sea marks are also common in the northern latitudes, especially in the island-strewn waters of Scandinavia and eastern Canada. They are placed along shores and on islands and islets. Usually painted white for improved offshore visibility, they serve as navigation aids. In Sweden, they are called kummel, in Finland kummeli, in Norway varde, and are indicated in navigation charts and maintained as part of the nautical marking system.^[26]