Nepal is a landlocked country in the mountains of South Asia, which is located in the southern foothills of the Himalayas (belongs to the southern bottom of the Qinghai-Tibet Plateau), bordering China to the north and neighboring with India on the other three sides. The Himalayas are the natural borders of China and Nepal. In addition to Mount Everest, there are eight of the world's top ten peaks on the Sino-Nepalese border.
Kathmandu, referred to as Kadu, is the capital and largest city of Nepal, located in the Kathmandu Valley, at the confluence of the Bagmati River and the Bishnumati River. Surrounded by mountains, the average elevation is 1,400 meters (4,600 ft) above sea level. Founded in 723 A.D., Kathmandu is an ancient city with a history of more than 1,200 years. Traveling to Kathmandu, Nepal from Lhasa, China is quite convenient now. Visitors can travel by air or by bus/coach.
There are three airports in Nepal, namely: Tribhuvan International Airport (KTM), Lukla Airport (LUA) and Pokhara Airport (PKR). Located in Kathmandu, Tribhuvan International Airport (KTM) is the only international airport in Nepal. The airport is small and about 6 km from the center of Kathmandu. If you travel to Kathmandu from Lhasa by air, there is only one direct airplane from Gonggar Airport in Lhasa, which departs at 11:50am and the journey takes about 2 hours with the airline carrier is Air China Airline.
If you want to go to Kathmandu by road, the best way from Lhasa is by driving along the Tibet Friendship Highway (China Nepal Highway). It is the only international highway in Tibet. It is also known as the Friendship Highway. It is an 800 kilometers scenic route connecting the capital of Tibet Lhasa with the Chinese/Nepalese border at the Sino-Nepal Friendship Bridge between Zhangmu and Kodari. It starts at Lhasa, going through Shigatse, Lhaze, Tingri, Everest and Zhangmu, and ending at the defense highway of Kathmandu. Usually, it takes about 3 days to drive to the Friendship Bridge (the border of Nepal & Tibet) from Lhasa.
To be noticed that Non-Chinese nationals are not allowed driving the intercity buses in Tibet. And one must be accompanied by a local tour guide. It is not recommended to travel by buses, because it takes a too long time and you may be exhausted or get sick on the way. In Tibet, getting sick is a serious thing for travelers.
There are choices to take buses to get to Kathmandu from Lhasa: one is a direct way and the other is a transfer way. Traveling by bus is a time-consuming way. So you must be prepared for this.
Visitors can take Sino-Nepal international express bus from Lhasa to get direct to Kathmandu, which is the most convenient route. The express bus only departs once a week at Friday during off-season and there will be one more which departs at every Tuesday in the peak season.
The second way is more flexible in departing time. Visitors can take bus from Lhasa to get to Shigatse first. Then transfer to a bus which leaves for Zhangmu County, from where you can exit at the port. There are a lot of buses which depart from Lhasa Xi Jiao Bus Station in Lhasa to arrive at Shigatze. It should takes about 4 hours and then you can spend a nigh there. Next, you can catch a bus to get to Zhangmu and it takes about 15 hours. After get through the exit, you can catch a Jeep to Kathmandu nearby.
There are SUV cares leaving for Zhangmu County from Lhasa. Zhangmu County is located at the border of China-Nepal, from where you can go through the exit. One can find this kind of cares near to Consulate General of Federal Democratic Republic of Nepalin in Lhasa. The journey takes about 15 hours. Upon your arrival at Zhangmu, you are supposed to spend a night there and get through the exit next day. After get through the exit, you can catch a Jeep to Kathmandu nearby.
No matter where you are from, you should guarantee your Tibet entry permit in advance.
Before you get on the transport vehicle, make sure that your Nepal visa is pre-prepared. Or you can not pass the exit.