The Fourth Doctor learns Tibetan. (TV: The Creature from the Pit)
Tibetan was a language primarily used in Tibet. The Third Doctor displayed a basic knowledge of the language to the point where he could greet K'anpo Rimpoche. (TV: Planet of the Spiders)
While in a pit on Chloris however, the Fourth Doctor was unable to read Everest in Easy Stages as it was written in Tibetan. Because of this, he began reading Teach Yourself Tibetan. (TV: The Creature from the Pit)
