North of Tibet, bordering on Pakistan and Afghanistan, lies Xinjiang: a vast 20% of China's area, comprised of the terrible Taklamakan Desert (home to untapped petroleum and China's nuclear tests) ringed with oases fed by mountain snows. Through two valleys north and south of the desert ran the most difficult portion of the medieval Silk Road from Xian in central China to Damascus; today, irrigation tunnels from the surrounding mountains--some in use for 500 years--supplement local water to grow prized fruits and vegetables, supporting 1% of China's total population--mostly the predominant Uighurs; nomadic Kazakhs, who crossed the long border with the USSR in the 30's; and more recently arrived Han Chinese settlers from the east. The Conklins (Paul took his sons on this Smithsonian-sponsored expedition as a college graduation gift) traveled by train from Xian through Xinjiang, photographing the forbidding desert, the friendly people, and the colorful oasis culture. Ashabranner (who did not go along) sets the journey in historical and cultural context, enlivening his account with direct quotes and the Conklins' personal experiences. Though it lacks the immediacy of a firsthand account, his narrative is informative and intelligent. The photos, on almost every spread, are excellent; like the text, they leave the reader thirsting to know more about this fascinating, little-known area. Bibliography; index.