Ever seen a place that looks like Mars, but it’s right here on Earth? Welcome to the Flaming Cliffs, deep in Mongolia’s Gobi Desert. Locals call them Bayanzag, and they really do light up at sunset.

Where a family’s prized possessions are their cows and sheep, second only to the horses—and maybe a pair of binoculars—strength has never been in numbers. The world’s last nomads have lived in harmony ...