Today I learned that air planes avoid the Tibetan plateau. This is due to the Aviation history and regulations, as well as general safety. The Tibetan plateau is on average more than 4,500 meters high or 14,700 feet. While international flights usually travel above 30,000 feet, it’s an emergency procedure that in case of an carbine depressurisation the flight should descend down to 10,000 feet. Doing this while being above the Tibetan plateau is especially difficult due to its size of 2,500,000 square kilometres, the already mentioned average heights, and the fact that there is only one airport in the entire plateau, that would allow larger machines, that are usually used for international flights, to land.
I came across this by watching a random YouTube video in the recommendations about exactly this topic. It goes into much more details and also looks closer into the history and further reasons for this avoidance.