The Sichuan–Tibet southern line — National Highway 318 from Chengdu to Lhasa, roughly 2,100 kilometers of it — is the road journey Chinese travelers romanticize above all others. It crosses the Hengduan Mountains range by range, dips from 4,000-meter passes into subtropical river gorges, threads the Salween, Mekong and Yangtze headwaters, and finishes on the Tibetan plateau. It is also a serious undertaking: altitude, weather and long empty stretches demand planning, and for foreign travelers a Tibet Travel Permit and an organized vehicle are not optional.
