I didn't know that Bessac was an Anthropologist for the CIA

This makes sense to me because Arcane from the planet New Deva is also an anthropologist sent to earth around 1987 to study people here to see what the galaxy can learn that might be useful for them from Earth Cultures and ways of doing things.

So, likely Bessac was one of the first anthropologists from the U.S. to actually Reach Tibet Alive because many people died then from the altitude then.

For example, even in the 1980s a member of Father Charlie's church (a friend of mine now passed away) wanted to go to Tibet in her 70s. However, this was not a practical thing to do because when she landed in Lhasa in her 70s she was dead from the altitude within 15 minutes at 12,000 feet there.

So, this happens to many people above around 8000 to 10,000 feet depending upon their health, lung capacity and other things healthwise.

Even when I climbed Mt. Shasta at age 22 I realized I had to breathe about 2 to 3 times faster not to get airsick from the altitudes of 10,000 feet to over 14,000 feet in altitude there. If you don't breathe faster you start to get air sick from oxygen deprivation and this can get really serious when people also go into Hypothermia from cold and altitude at the same time and start hallucinating.

So, unless you are extremely healthy to begin with don't even attempt to go to Tibet because the lowest altitude there is 8000 feet and the highest of course is Mt. Everest at about 30,000 feet which is the altitude jet passenger planes fly at. 

My friend in 1985 who met us at the Kalachakra tantra who was from Alaska said he took a bus to Lhasa (and we were all in our 30s then so still pretty healthy) and he came across in his bus a whole bus full of dead people who had died from lack of oxygen and exposure there including the driver when the bus broke down at a 20,000 foot pass in between Kathmandu, Nepal and Lhasa, Tibet. When he told me this I didn't want to accidentally kill my whole family and I decided not to travel into Tibet than in 1985 or 1986 as a direct result. I haven't regretted this decision by the way as I have heard more and more stories of people dying from the altitude there including good friends of mine who barely made it out of there alive.