I was reading one of those old 19th century articles about somalia. One of them mentions a 9 mile long aqueduct in ruins since people used those stones for their graves. My question is how did we forget this kind of technology was it ? I suspect if you looed all throughout somalia you would find simialr examples like this and or the ajuran. It makes no sense since to create an aqueduct like that requires enormous manpower. I sort of understand why the somali people living in the 19th century said it was the work of a forgotten race. It seems like post 1500s we regressed back millenia. Sort of like the khemr empire and angora wat