It is not possible to enter in Tibet as backpackers, so it needs the help of a Travel Agency. Briefly speaking, to visit Tibet you must follows an organized trip plan everything before. You’ll need a Chinese Visa and a Visa/Permit to visit Tibet. Both it’s better to obtain through the travel agent you’ll choose.
 

If someone wants to travel in Tibet it’s important to know how to get the permit to enter Tibet.

Click here for more information about Tibet Permit: /customer-center/tibet-travel-permits.htm