China considers Tibet as a region of China, but a Chinese visa is not sufficient for the province. Regulations are constantly changing, with a constant: you must apply for a permit to Tibet Tourism Bureau before entering the autonomous region of Tibet.
To do this, you must be part of a group and submit your application via an agency – who will sell you a license with a circuit in Tibet.
The cheapest solution is usually to take a “formula” between Lhasa and Chengdu air or rail from Chengdu, Xi’an and Xining. In these cities, most hostels are in charge. These formulas include sometimes a few nights in Lhasa. In the best case, they summarize the license and ticket. Upon arrival in Lhasa, “groups” temporary separate. Feel free to organize your onward journey.
From Kathmandu, you will join a circuit to obtain the license of Tibetan Tourism Bureau. Your Chinese visa will be canceled and replaced by a group visa on loose leaf. You can obtain a copy upon request, allowing you to move freely as an independent at the end of the tour, for the period indicated in the visa group (which may be limited to 2 additional weeks).
Once in Tibet, you must be licensed to access any other place Prefecture Lhasa and Shigatse cities and Tsetang – and thus places like the base camp of Mount Everest (EBC), Samye Sakya and Mount Kailash. This permit can only be obtained by registering a circuit through an approved agency