The Senegambian stone circles, also known as the Wassu stone circles, are groups of large stone circles found in the Gambia, north of Janjanbureh, and in central Senegal. These circles cover an area of 30,000 square kilometers (12,000 square miles). Sometimes, they are divided into two groups: the Wassu circles in the Gambia and the Sine-Saloum circles in Senegal. This division is based on national borders and does not reflect any other differences. The sites include more than 1,000 stone circles and mounds, with 1,145 recorded locations from a study in 1982. These circles are spread over a region 350 kilometers (220 miles) long and 100 kilometers (62 miles) wide. They are the largest collection of stone circles in the world and form a large sacred landscape that was used for more than 1,500 years. In 2006, these sites were added to the UNESCO World Heritage List.

Description and history

The stone circles and other large stone structures found in Senegal and Gambia are often grouped into four main areas: Sine Ngayène and Wanar in Senegal, and Wassu and Kerr Batch in the Central River Division of Gambia. These four areas include about 29,000 stones, 17,000 monuments, and 2,000 individual sites. The monuments were originally upright blocks or pillars, mostly made of laterite, with smooth surfaces. Some of these pillars have collapsed. The monoliths are arranged in circles, double circles, or rows, and some stand apart from the circles, usually to the east. Stones that stand apart are called frontal stones. When frontal stones form two parallel, connected rows, they are called lyre-stones.

Researchers are unsure of the exact time these monuments were built, but they are generally believed to have been created between the 3rd century BCE and the 16th century CE. Burial mounds near the Wassu complex have been dated to between AD 927 and 1305, but it is unclear whether these mounds were built before or after the stone circles. Archaeologists have found pottery shards, human remains, and grave goods near the megalithic sites. A small collection of these items is displayed in the British Museum, donated by colonial administrator Richmond Palmer.

The construction of these stone monuments suggests a society that was organized and prosperous, as building such structures required significant labor. The stones were taken from laterite quarries using iron tools, though few quarries have been directly linked to specific sites. After extraction, identical pillars were made, either cylindrical or polygonal, with an average height of two meters and a weight of seven tons.

Historians and archaeologists disagree about who built these structures, partly because no existing group claims their ancestors were responsible in their oral histories. The monuments share similarities with buildings and burial practices of the Serer, Konyagui, and Bassari people. Some scholars have ignored complex evidence and claimed their ethnic group built the monuments.

The Senegalese historian and anthropologist Cheikh Anta Diop suggested the Serer people built the monuments and similar structures across the Sahel during a migration from the Nile River valley. Wolof and Fula oral traditions also credit the Serer as builders. However, the Serer people themselves attribute the monuments to the Soos wee or Soos waa Kaabu, meaning "men from the beginning of Kaabu." These "Soos" are described in Serer oral history as the original inhabitants of the area, though their language and culture are debated.

Some historians believe the Soos were a group speaking a Mande language who migrated from the Wagadu Empire to escape a drought around the end of the first millennium CE. According to this theory, the Soos were later assimilated or displaced when the Serer people arrived in the 11th century, though the newcomers may have adopted their burial customs. The term "Socé" is now used to describe Mande-speaking people in Wolof and Serer languages.

Babacar Sédikh Diouf noted that the Serer people have a matrilineage named "Soos," whose members may have been the first to migrate to the Sine-Saloum region. The Serer people have used funerary houses similar to those found at the Wanar site up to the present.

Another theory suggests the stone circles were built by cultures that were later pushed south by the Serer, Mandinka, and Wolof. The Bassari people, who now live in southeastern Senegal, still bury important community members in stone funerary huts with construction methods and burial practices similar to those found at the stone circle sites.

World Heritage Sites

• Stone circles of Kerr Batch 13°45′16″N 15°04′05″W / 13.754565°N 15.068131°W / 13.754565; -15.068131
• Stone circles of Wassu 13°41′29″N 14°52′23″W / 13.691525°N 14.873111°W / 13.691525; -14.873111
• Stone circles of Wanar 13°51′23″N 15°37′04″W / 13.856425°N 15.617642°W / 13.856425; -15.617642
• Stone circles of Sine Ngayène 13°41′43″N 15°32′07″W / 13.695278°N 15.535278°W / 13.695278; -15.535278

Kerr Batch is an area in Gambia’s Nianija district that includes nine stone circles and one double circle. One unique stone at Kerr Batch is V-shaped and broken in three places. It was part of a line of stones and was repaired during an archaeological expedition in 1965 led by Paul Ozanne. During this expedition, the team also excavated the double circle at Kerr Batch.

Wassu is located in Gambia’s Niani district and includes 11 stone circles and their associated frontal stones. The tallest stone in this area is 2.59 meters high. The builders used knowledge of local geology to find sources of laterite stones and had the skill to extract them without breaking them. Excavations from 1964 and 1965, led by Evans and Ozanne, found burials that helped date the monuments to between AD 927 and 1305.

Wanar is in Senegal’s Kaffrine Department and includes 21 stone circles and one double circle. One-third of all Senegambian lyre-stones are found here. The monuments are believed to mark burial sites, and the stones were added later for rituals. Construction of this area occurred between the seventh and fifteenth centuries AD.

A study estimated that the double circle at Wanar was built between the twelfth and thirteenth centuries AD. In 2008, an excavation found two types of burials: simple pits covered with mounds and more complex, deeper pits. Perishable materials like brick and plaster were found, suggesting funerary houses existed at the time.

At Wanar, two types of stones were found: tall, slender cylindrical stones and shorter, trapezoidal stones. Fallen monoliths in the inner ring of the double circle suggest that dry stone may have been placed beneath them. When the structure collapsed, the stones fell outward. Pottery shards found in different layers of earth indicate that some activity occurred after the dry stone fell but before the monoliths collapsed.

Researchers believe the monuments at Wanar went through three phases: Phase one involved digging graves and covering them with mounds; Phase two included raising standing stones around the mounds; and Phase three involved adding frontal stones. These monuments may also have been used for rituals, with pottery placed around them.

Sine Ngayène is the largest area, with 52 stone circles, one double circle, and 1,102 carved stones. Single burials here are older than the multiple burials linked to the stone circles. It is located northwest of Sine-Saloum, Senegal, at 13°41′N, 15°32′W.

In 2002, an archaeological project found iron smelting sites and homes near Sine Ngayène. These homes were grouped in clusters of 2–5 and dated to the same time as the monuments. This suggests small, independent communities existed nearby. The site has a Y-shaped central axis, with a double circle (Diallombere) at the center.

The site was once surrounded by burial mounds that eroded over time. Evidence shows burials occurred first, followed by the erection of stones. Frontal stones were often placed on the east side of the circles. Researchers identified four cycles of activity, based on layers of materials and monument construction. These cycles are dated from AD 700 to 1350.

The first cycle (700–800 AD) included a large pit with human remains, iron spearheads, and a copper bracelet. A mound was built over the pit, and stones were added later. The second cycle (800–900 AD) had another pit with long bones and skulls. The third cycle (900–1000 AD) included an inner circle of monoliths and a laterite slab, possibly used as a sacrificial table. The monument evolved from a burial ground during this time.