To expand: I was in Chengdu in September, looking to get into Tibet. As of then all travel in Tibet for foreign nationals required a permit. To get a permit required you be in a tourgroup (which could be just you) but had to be guided all of the time. This included "trekking" (didn't bother with climbing). Unlike in the past these rules were rather inflexible and few people had successfully skirted them. The only person I met who had was Chinese-American and spoke Mandarin fluently. Based on 2nd hand reports little has changed in the last 6 months so I'd suggest "fuck China"
Check out Kyrgyzstan/Kazakhstan instead