Travelers will find that most of China is accessible. However, areas that are either totally or partially off-limits, and may require a permit from the PSB, include Lushun (Liaoning), Xanadu (Inner Mongolia), and parts of Shennongjia (Hubei). It is recommended to check with the PSB before setting out to western Sichuan, where the rules of access are not yet fixed. In Tibet, traveling out side Lhasa prefecture requires a Tibetan Tourism Bureau (TTB) permit as well as a separate travel permit. Chinatravelfactbook.com can help you get TTB permit as well as a separate travel permit.