Get more details on: http://www.reisennachchina.com/provinz/tibet-reisen/
For the china travel the best option for a travel agency is Reisennachchina, which allows you to select package according to your choice and facilitate you with the best local guide. If you are planning to visit Tibet then you must know when it is best to Travel Tibet? And if you are planning for the winter season then it may be not so worthy, as in February and March for 5 or 6 weeks Tibet is closed for travellers due to heavy snow fall. This the only duration when the number of foreign travellers are at its least.
