Under consideration as a UNESCO World Heritage Site, Sakaro Sodo and other archeological sites in southern Ethiopia have the largest number and highest concentration of megalithic stele monuments in Africa. Rising as high as 6 metres, the ancient stone monoliths have now been dated to sometime during the first century CE - 1,000 years older than previously thought. French scientists in the 1990s had estimated a construction date of around 1100 CE.
     The standing stones range widely in size, function, and arrangement in the landscape. A few have intricately wrought faces and other anthropomorphic designs carved into the stone. Many have fallen. Some are broken. Despite the large number of monuments in a small area, it remains one of the least studied archaeological sites in the world.
     Researchers also determined where the ancient builders likely quarried the stones, and identified the earliest known sources of obsidian artefacts recovered from the stele sites - most from around 300 kilometres to the south in what is now northern Kenya.
     The new construction dates of the monuments appear to coincide with the arrival of domesticated animals in the region.  

Edited from Washington State University, ScienceDaily (9 December 2021)