The gardens made on the fringes of Central Asia in the past 5000 years form a great arc. From the Fertile Crescent, it runs west to Europe and east to China and Japan. Asia's fringe was a zone of interchange: a vast landscape in which herders encountered farmers and the design of symbolic gardens began. It appears that as they became settlers, nomads retained a love of mobility, hunting and the wild places in which their ancestors had roamed. Central...