KHARTOUM, Sudan — Every winter they come and go, like birds migrating south. Most of them nest in downtown Khartoum’s old Acropole Hotel, but they’re not here to rest. They’re here to work in Sudan’s blistering deserts, and the past few years have yielded outstanding results.

For many people around the world, Sudan conjures images of war, instability, drought and poverty. All of those things exist here, often in tragic abundance. But lost in the narrative are the stories of the ancient kingdoms of Kush and Nubia that once rivaled Egypt, Greece and Rome.

Lost to many, that is, but not to the archaeologists who have been coming here for years, sometimes decades, to help unearth that history....