Located in Gambia, north of Janjanbureh and center of Senegal, Senegambia Stone Circles covers an area of about 30.000 square kilometers. Researchers are not sure when these monuments were built, vestiges are dated between the 3rd century BC and 16th century AD.
The four groups of monuments (Wassu and Kerbatch in Gambia, Wanar and Sine Ngayene in Senegal) count 93 circles of laterite pillars that surrounds tumuli - burial mounds; there are about 29,000 stones 17,000 monuments, and 2,000 individual sites. At the excavation of tumuli were found shards of pottery, human burials, some engraved objects and metals.
Monoliths are placed in circles, circles double in rows or isolated. The construction of stone monuments proves that there was a society organized and thrive, able to produce the volume of work required to build such structures.
The stones were extracted from laterite quarries using iron tools, then they carved pillars identical either cylindrical or polygonal, with an average of two meters tall and weighing seven tons. Manufacturers of these megaliths are unknown. Possibly Serer people because they still use funeral homes similar to those found in Wanar, but other hypotheses have been submitted too.
Wassu is located in Gambia and consists of 11 stone circles, the tallest pillar is about 2.6 meters high.
Kerbatch consists of nine circles of stone and a double circle.
Wanar consists of 21 stone circles, a double circle and numerous lyre-stones. Excavating the double circle were found simple graves, sealed with a mound or complex graves, deeper and with narrow opening.
Sine Ngayene is the most extensive of the four groups. It has 52 stone circles, a double circle and over 1,000 carved pillars. The site is Y-shaped, with double circle in center and was surrounded by hundreds of mounds that have eroded over time.
Researchers found that some graves were individual, others were mass graves where they were buried many bodies, without order or precise alignment, suggesting an epidemic or a sacrifice.
Nearby sites were found laterite quarries, but cannot be precisely from what quarries come a specific pillar.