@Atrocious
Frankly, because the Chinese government has been known to react harshly to some very weird stuff wherever Tibet or Taiwan is concerned. And anything with customs would give them handy cover to reject her.
However, as totally awesome as a Million-Lhasa March on Beijing would be, I have neither the intention nor the ability to coordinate one. The most my 17-lb girl would menace the streets of Beijing would be to go on the sidewalk once in a while, and I'm very consistent about picking up after her.
EDIT: According to About's China Travel page:
Arriving in China with Your Pet: The pet owner should collect the pet at arrival and then proceed to the customs counter to declare the pet to the Customs Counter to declare your animal to the customs officials.
Quarantine Period: There is a mandatory quarantine period of 30 days. According to some information, the pet will be kept in a quarantine station for 7 days and the remainder of the time, if the pet passes inspection tests such as rabies, can be spent at home with the owner.
Owners should be aware that during the pet's time in the Quarantine Station, the owner will not be allowed to visit or see the pet. The owners will also be required to pay fees for the quarantine time in the neighborhood of 2000rmb to cover food and expenses.
Arrival Documentation: In addition to the proper entry visa in the pet owner's passport, the owner is required to show two documents for the pet:
- Animal Health Certificate
- Vaccination Certificate
Changes in Policy: If you are moving to China and are considering bringing your pet, then you should check with your relocation company to be sure to understand all the latest regulations regarding bringing a pet to China. Rules can change without notice.
(The rest of my google-fu brought up nothing about China banning Lhasa Apso's from the mainland, so you should be free to take her/him.)
edited 16th Jan '11 5:13:47 PM by AtrociousMILF
I Read That As KHSAS Banned in China.
China bans some very strange things
if they think it could symbolize the tiniest modicum of support for things they don't like.

I can't help but wonder this, being a lhasa owner with a perennial interest in Asia. I note that there are no pages on lhasa apsos in the Chinese Wikipedia. When I asked my Chinese friends about what sort of logic would go into that, given that it's a native breed, they said that lhasas were probably grouped together with shih tzus, since they look so similar. But, if I were to travel to China with my baby girl and I needed to mention her breed somewhere on a vet form to show that she's had her shots, I would call her a lhasa apso, since that's what we call her here. Do you think the Chinese government would bar me from bringing her on that basis?
edited 16th Jan '11 3:53:20 PM by Clevomon