Deep in the Saharan desert, huge stone pyramids rise, monuments to ancient kings. But they aren’t in Egypt—these pyramids are far to the South, in Sudan. Far less well-known by either archaeologists or the public than their Egyptian counterparts, these pyramids rise in close-knit clusters at once grand sites like El Kurru, Gebel Barkal, and Meroe. Who built these pyramids? And why?

The pyramids in Sudan were built over a period of hundreds of years by a civilization known as the Nubians. The Nubians were initially conquered by the Egyptians and for centuries lived under Egyptian administration. After the Egyptian dynasties fell into dissaray, Nubia broke free and became its own empire, even conquering the Egyptians for a time. Throughout their history, the two societies maintained extensive trade and cultural ties, leading to the Sudan pyramids.

The first Nubian pyramid was built around 700 BC, much later than the great pyramids. After so many years of exchange, the Nubians worshipped Egyptian gods and kept many Egyptian traditions, even as Egypt itself faded as a power. The Nubian pyramids are smaller, typically less than 100 feet high, where the pyramid of Khufu is a whopping 440 feet tall. The Nubian pyramids have a steeper slope, a byproduct of Nubian shadouf-based construction. The shadouf, a simple counterweight crane, was set in the middle, and the pyramid went up around it; the crane could only reach so far so the base of the pyramid had to be small, mandating steep sides.

The differences do not end there. A 1897 British expedition to Gebel Barkal excavated inside a pyramid, and soon discovered that there was no burial chamber, as would be expected in Egypt. The burial chamber was actually underneath the pyramid, so the Nubian pyramids, rather than being tombs, were really enormous headstones. They are very close together, carefully aligned with certain stars. The pyramids had solid sides with a fill center, a very practical form of pyramid construction also used in Mesoamerica. In contrast, scientists have recently discovered how the Egyptian pyramids were built using wet sand.

Alas, the pragmatism of the Nubian builders might be the monuments’ undoing. The smaller-facing blocks that the Nubians used made a convenient source of building materials, and many blocks have been scavenged. Furthermore, the 1897 expedition noted that many of the pyramids had been truncated. This mutilation was the work of 1834 treasure hunter Giuseppe Ferlini, who found gold underneath a pyramid in Meroe. Hoping to go back for more, he decided to confuse his rivals by removing the tops of the pyramids.

Future would-be looters did the same, resulting in fields of pyramids with no point. Unfortunately, the truncation makes the internal structure vulnerable to the elements, and some of these mighty works are literally rotting from the inside out. Hopefully the legacy of greed from an earlier age can be overcome.