The green, green hills of Yemen? The verdant highlands of the southwestern Arabian peninsula, a product of seasonal monsoons, have yielded bountiful harvests for thousands of years, thanks to the Yemenites’ hydraulic ingenuity. Their terraced fields (shown here and in a previous photo) capture up to 40 inches of rainfall each year. The region’s Neolithic hunters and gatherers were the first to create artificial irrigation systems, and by the third-millennium B.C., Bronze Age settlers had established small hilltop settlements with planted terraces. With the rise of the first millennium B.C. Sabaean kingdom (possibly the homeland of the queen of Sheba), the area’s rich agricultural base and lucrative incense trade funded large-scale irrigation projects. When overland incense routes were largely abandoned in the first millennium A.D., severing trade links between Yemen and the great civilizations to the north, the Yemenite highland kingdoms sank into oblivion.