Passport
A passport is essential, and if yours is within a few months of expiry, get a new one now. You must have a passport valid for 7 months beyond the completion of the tour. Be sure that your passport has at least a few pages for visas and entry and exit stamps.

Travel Permit
Except a normal visa to China, foreign tourist who desires to visit Tibet has to hold The Alien's Travel Permit, which issued by Tibet/China Tourism Bureau.