I have just come back from China researching a sequel to The Hidden Monastery. I was in the far west in Yunnan province 3,700 meters above sea level in a town that has been renamed Shangrila. Even climbing up steps was hard work because oxygen at that height is limited. When you suffer from altitude sickness, you get a very bad headache and sometimes you feel like vomiting. The hotel I stayed at even had a special room called the Oxygen Bar where you could get hooked up to oxygen. This relieved the sickness within half an hour. What amazed me was that all the domestic animals wandered about the countryside freely. There were no fences. At dusk, the yaks, cattle, pigs and horses would make their own way back home where they would sleep under the farmhouses.