Hate to say, I have seen Tibetan script and even
old Tibetan script - don't think it is Tibetan. I am more inclined with BluErf - Chinese jibberish.
Also, they stick some of these things in the most acidic soil they can find - the fakers I mean - and can get real looking patina for half of the age. I may be wrong, but I am on the side of a copy.

Best to take it to a museum or "experts" who can see this thing up close and in person.