Two highways cross the eastern Tibetan Plateau between Chengdu and Lhasa. G318, the southern route, is the one most travelers picture: high passes, river gorges, forested valleys, the long run through Nyingchi. G317 bends north through Tibetan villages, monastery towns and open grassland. Serthar, where the red houses of Larung Gar pack onto a single slope, sits off the northern corridor and changes the shape of a north-route trip.
Two corridors
The routes split west of Kangding. G318 runs through Xinduqiao, Litang, Batang, Mangkang, Ranwu, Bomi and Nyingchi; G317 swings north through Danba, Luhuo, Dege, Qamdo and Nagqu. Chengdu to Lhasa is roughly 2,100 km on the southern road and 2,300 km on the northern. Neither figure says much about time. Mountain roads, weather and altitude set the pace, and a short map distance can take far longer than expected.
South or north
G318: landscape first
The southern route is the more straightforward introduction to the plateau. It passes Xinduqiao, whose light and poplar-lined streams have made it a base for photographers, Litang, a high grassland town, and the turnoff for Daocheng Yading, a detour that adds several days. Further west come Ranwu Lake, the forested Bomi section and the Nyingchi valley, where the scenery softens into farmland and pine.
Services are better developed along G318: more towns, guesthouses and repair options. The road still has teeth. Landslides are a real summer risk, and two sections need attention, the Tongmai stretch where the road follows a narrow river gorge and the switchbacks on the long descent from Yela Pass. Both are manageable in good conditions and should be treated with respect in rain or snow.
G317: monasteries and long valleys
The northern route is less about set-piece scenery than the texture of the plateau. Jiaju village in Danba, its stone houses stacked against the hillside, is the clearest introduction to Gyarong Tibetan architecture. Dege is known for its printing house and its place in Tibetan literary culture. Monasteries, mani walls and small towns appear between long stretches of grassland and river valley.
Distances are longer, settlements thinner and sleeping altitudes often higher. Some sections between Qamdo and Nagqu have a reputation for rough surfaces and slow going, so local advice beats a fixed timetable. G317 suits travelers curious about religious life and remote communities, and willing to accept that a comfortable hotel will not appear every night.
Adding Serthar
Serthar, written Seda in Chinese, is a county in Ganzi, Sichuan. Most visitors come for Larung Gar, the Buddhist academy whose slopes are covered in thousands of small red residences. It is a working religious community, not a sight. Photography may be restricted, and ceremonies, residences and sky-burial sites are not spectator events. Access rules change, so confirm the current situation with local authorities and your accommodation before setting out.
At around 4,000 meters, Serthar is not a place to rush. Two nights allow a calmer visit and give the body time to adjust. The road in from Luhuo and Wengda is a side trip from G317 rather than a through-route to Lhasa, so build the detour into the schedule instead of squeezing it into a long driving day.
Route shapes
Southern corridor. Chengdu → Kangding → Xinduqiao → Litang → Batang → Mangkang → Ranwu → Bomi → Nyingchi → Lhasa. Allow nine or ten days at minimum, more if you add Yading. This is the simplest choice for a first crossing and the one with the most consistent services.
Northern corridor with Serthar. Chengdu → Kangding → Luhuo → Wengda → Serthar → Dege → Qamdo → Dengqen → Nagqu → Lhasa. Ten to twelve days is a more realistic frame. You get a deeper look at Tibetan cultural life, and you pay for it in rougher roads, higher nights and fewer fallback options.
Siguniang and Serthar, then south. Chengdu → Siguniang → Danba → Luhuo → Serthar → Dege → Qamdo → Baxoi → Ranwu → Bomi → Nyingchi → Lhasa. This links the northern cultural circuit to the southern landscape route, joining G318 near Baxoi. It is the most varied option and the most demanding. If you have little experience on narrow mountain roads, hire a local driver rather than self-driving.
Altitude and weather
Kangding is a useful first night before climbing higher. Litang and Nagqu sit at demanding elevations; avoid making either your first high-altitude sleep. Ascend gradually, drink water, go easy on alcohol and rest when the body asks for it. Headache and poor sleep are common. Breathlessness at rest, confusion or vomiting are reasons to descend and seek help. Travelers with heart or lung conditions, uncontrolled diabetes, pregnancy or a previous history of altitude illness should get medical advice before going.
May to October is the main travel season, though July and August bring the heaviest rain and the greatest landslide risk. Winter can be clear and bright, with cold nights and snow or ice on the passes. Check forecasts and local road reports before each stage, and avoid night driving on mountain roads.
On the road
Fuel up at county towns and keep track of the next available services. Livestock, trucks and cyclists share the road; pull into designated lay-bys rather than stopping in the traffic lane. A driver who knows the route earns their fee in rain or on unfamiliar high passes. Self-driving demands experience with narrow mountain roads and patience when conditions change.
Accommodation ranges from simple guesthouses to hotels in larger towns. In peak season, book ahead, and confirm access and road conditions with official sources rather than relying on older trip reports.
Permits for international visitors
Ganzi and Serthar lie in Sichuan, but onward travel into the Tibet Autonomous Region brings additional requirements. Foreign passport holders generally need a Tibet Travel Permit, usually arranged through a licensed tour operator, and some areas require further permits. Rules and processing times can change, so check well in advance with an official source or a reputable operator. Monastery access is a separate question from road permits.
Pace
The pleasure of these roads is not a checklist of viewpoints. It is watching pine forest give way to grassland, a monastery appear above a river bend, a truck grind up a pass while cyclists wait for a clear stretch. Plan for weather, allow for altitude and leave room for the unplanned stop.
How this guide was made
This guide combines structured research and automation with source and duplication review. Dates change; verify time-sensitive details before travelling.