Well Vietnam (along with Burma and Hong Kong and no doubt others) is one of the main entry points to the Chinese mainland for smuggled products, so it's quite possible that this is the intention with stuff coming from Czechia as well.
I would assume that any country with an ethnically Chinese minority population (Malaysia etc) would have significant amounts of TCM use. I also assume that countries like Vietnam and Korea which have historically fallen within China's sphere of influence also have or had a lot of use. That is pure supposition though; a tiny bit of research doesn't throw up anything about this.
@baboon Since I know you have seen this thread do you have anything to add, correct or comment on?
Many TCM doctors said "A real doctor is firstly a compassionate person thus will never encourage people to drive another species to extinction." "There aren't any medicinal materials that are irreplacable, there are only foolish doctors don't know how to replace them. Thus if a doctor ask you to use endangered species, it only proves that he is a cheat." Moreover, acording to the research of real TCM doctors, rhino horn is not listed as an important material in ancient medicine book, it is only hyped in recent times by some incompetent "doctors". Because most patients cannot afford such a expensive material, they will think their incurabilities are not the fault of the doctor, but their poverty. For the tiger bone, the Chinese TCM doctors had found the mole rat bones were perfect replacements for the tiger bones nearly twenty years ago.
On the other side, there is still a rhino farm in Yunnan with hundreds of white rhinos from South Africa, and it is said that they breed well. To made the rhinos feel more at home, they even added giraffes and zebras into the rhinos' pastures. They placed many special grinding discs around the pastures and when the rhinos rub their horns against those grindling discs, the debris from the horns will fall into the collecters beneath. I don't believe there are any medicine effects within the rhino horns, but I also don't dislike the idea of farming rhinos, the only problem is, both TCM hospitals and buyers don't care about the origin and legal identification of the horns, thus many sellers will use horns from wild-poached individuals and mixed them within the legal horn powders from the rhino farm.