Medieval-Style Fortifications Are Back in the Sahel
5th July 2026
ot much remains today of the walls, ramparts and moats that once surrounded Benin City in southern Nigeria. Yet for centuries these giant earthworks—second in length only to China’s Great Wall among man-made structures—bespoke a mighty civilisation whose authority extended across much of west Africa. By the standards of pre-colonial Africa, the Benin state was exceptionally strong: erecting the wall in a single dry season might have required mobilising as many as 5,000 men, each working ten hours a day. But as the empire withered and eventually succumbed to British invaders in the late 19th century, most of the earthworks vanished. So did those of many other fortified towns across west Africa.
Now they are returning. Since the mid-2010s, as jihadist insurgencies have spread across northern Nigeria and the Sahel, defensive earthworks have risen up around towns and cities. Many are so extensive they are clearly visible in satellite images. According to new research by Olivier Walther and Steven Radil, geographers at the University of Florida, all urban centres in north-east Nigeria with populations of more than 10,000 are now secured by trenches. Most big towns there and in the Lake Chad basin are surrounded by sand berms up to three metres high.
Imagine how peaceful the world would be if the Religion of Peace didn’t exist.