One historian from ancient Greece, Diodorus Siculus, wrote about the Nabataeans, painting a vivid picture of a strong community of 10,000 warriors. He said the Nabataeans entirely rejected the idea of agriculture and permanent houses. Instead, they focused on their pastoral roots, as well as the lucrative trade in spices, frankincense, and myrrh — all gathered from the region that’s known today as Yemen. Photo Credit: Adél Békefi / Getty Images