How could such an abundance of life and ancient culture spring from a geography as rugged and desolate as Peru’s? Deserts line the entire coast, the Andes spring to well over 6,000 meters, and the Amazon jungle fans out thousands of kilometers toward the Atlantic Ocean.

Peru’s foreboding terrain belies its extraordinary fertility. Peru’s arid coastal climate is caused by the frigid Humboldt Current, which sucks moisture away from the land. But these Antarctic waters also cause a rich upwelling of plankton, which in turn nourishes one of the world’s richest fishing grounds. Peru’s earliest cultures took root near the ocean and depended on mollusks and fish for their survival.

Peru’s snow-covered mountains and high passes would appear to be an impediment for the spread of advanced cultures. But the slow melting of the snowpack provides the desert coast with a vital source of year-round water. Once they developed irrigation technologies, Peru’s early cultures could cultivate crops and began to spread up into the fertile coastal valleys and the mountains. The ingenious aqueducts at Nasca, which carry mountain water for miles underneath the desert floor, are still in use today.

In the more moderate topography of North America and Europe, temperature differences and climate zones are largely a question of latitude—Florida produces oranges, while Kansas produces wheat. But in Peru, climate zones are caused by altitude, not latitude. In places Peru’s coast rises from sea level to over 6,000 meters (19,700 feet) in less than 100 km, creating a variety of climates apt for fruits, vegetables, grains, and potatoes. The same phenomenon occurs to an even greater extent where the Andes plunge into the Amazon, a dizzying range of ecosystems that nourish a whole new set of fruits and a huge storehouse of medicinal plants, including the coca leaf.

As a result of Peru’s vertical geography, trade routes from the Amazon over the Andes to the desert coast were key to the flourishing of Peru’s ancient cultures. The Chavín culture, based in the high hills near the Cordillera Blanca, pictured pumas, snakes, caimans, and other Amazon animals in their enigmatic carvings. They traded their high-altitude grains and potatoes for dried fish and vegetables from the coast.